CN113037223B - A Broadband Differential RF Power Amplifier with Second Harmonic Suppression - Google Patents

Abstract

The invention relates to a broadband differential radio frequency power amplifier with second harmonic suppression, which comprises a broadband input balun, a driving amplifier, a T-shaped matching network, an output amplifier, a harmonic suppression matching network and a broadband output balun. The broadband differential radio-frequency power amplifier with the second harmonic suppression converts one single-ended signal into two differential output signals through a broadband input balun, adopts a driving amplifier, a T-shaped matching network and an output amplifier to improve the output capacity of the power amplification power of the output signal, and adopts a harmonic suppression matching network to process the second harmonic of the output signal, so that the influence of the second harmonic on the overall performance of the radio-frequency power amplifier is reduced better, and the performance indexes such as efficiency, linearity and the like are improved; synthesizing one path of signal output by two paths of output signals of the broadband output balun pair; the broadband differential radio frequency power amplifier realizes the combination of a harmonic suppression network and a broadband balun, and improves the working bandwidth of the power amplifier.

Description

A Broadband Differential RF Power Amplifier with Second Harmonic Suppression

technical field

The invention relates to the technical field of power amplifiers, in particular to a broadband differential radio frequency power amplifier with second harmonic suppression.

Background technique

Wireless communication is in an era of rapid development. Various consumer electronics products have added wireless communication functions, and many cities are also building wireless cities. In terms of mobile communication, due to the increasing requirements for communication speed, communication standards have been improving, and the fifth-generation mobile communication (5G) technology has gradually entered people's lives, which can quickly transmit high-quality video, audio, image and other data. The information radio frequency transceiver is one of the most important modules in the modern wireless communication system, and the power amplifier located at the end of the transmitter is the core component of the wireless transceiver, and its performance directly affects the quality of the signal, the transmission distance and the energy consumption of the system . The performance indicators of power amplifiers mainly include output power, efficiency, bandwidth and linearity.

Since the future communication trend requires higher data rate and wider coverage, and the output power of the power amplifier is directly related to the longest transmission distance of the signal, high power is the basic requirement for power amplifier design. After the processing technology of the power amplifier chip is determined, the design of the power amplifier chip is mainly to obtain high output power. The common method of designing the power amplifier chip is to connect the transistors in parallel to increase the maximum allowable output current, but this will lead to a decrease in the load impedance. This results in a higher impedance conversion ratio, higher matching loss, increases the difficulty of output matching and reduces the bandwidth of the power amplifier. In addition, the power amplifier is one of the main energy-consuming components in the wireless communication system, and its efficiency largely determines the overall efficiency of the wireless communication system. The low working efficiency of the wireless communication system will cause a lot of energy loss, and the heat generated will deteriorate the performance of the power amplifier, and if it is powered by a battery, it will also shorten the service time and life of the battery. Therefore, to improve the efficiency of the power amplifier from the perspective of a single tube, it is possible to reduce the conduction angle of the power amplifier to make it work in the switch mode. However, although the conduction angle is too small, the efficiency can be improved obviously, but the output power of the power amplifier will be reduced. and linearity.

Since the most important transistor in the power amplifier, and the transistor is a nonlinear device, its nonlinear characteristics will affect the output signal quality of the power amplifier, so it is necessary to take into account the linearity of the power amplifier while considering the output power and efficiency of the power amplifier. The harmonic component generated by the large signal amplified by the transistor is the most important factor affecting the linearity of the power amplifier. The existing typical differential power amplifiers input the differential signals into two amplification links respectively, so that at the same output power level, the load line impedance of the differential power amplifier is 4 times that of the traditional single-ended structure power amplifier, and the impedance conversion ratio is The substantial reduction is beneficial to avoid the large insertion loss and narrow bandwidth that may be introduced by the matching network, and also reduces the design difficulty of the matching network.

However, in the design of single-ended PA (single-ended input and single-ended output power amplifier structure), since the standard silicon-based process does not have low impedance grounding, the emission caused by the bonding wire inductance in the power amplifier structure of single-ended input and single-ended output Extremely degraded. A low-impedance ground is usually made by connecting several bond wires in parallel, however, it is usually limited by the frequency, the mutual inductance between the bond wires, and the number of pads available for down-soldering. The differential design topology can effectively reduce the emitter degeneration inductance due to virtual ground. Existing differential power amplifiers usually use simple LC baluns or transformer baluns to perform conversion and impedance matching between single-ended signals and differential signals, as shown in Figure 1 . The traditional LC balun has a simple structure, but its bandwidth is narrow, and it is difficult to design flexibly. The transformer balun is usually integrated inside the chip and occupies a relatively large area, which affects the cost and flexibility of design layout. Moreover, since the antenna is single-ended, it is necessary to add a balun between the antenna and the power amplifier structure with differential single-ended input and single-ended output to convert the differential signal into a single-ended signal, and the amplifier with a differential structure with single-ended output cannot achieve differential The structure takes advantage of the fact that the even harmonics (common-mode signals) cancel each other out when differentially output to the load.

In addition, existing power amplifiers are often combined with a cascode structure to further increase the withstand voltage capability of the transistor. The common node of the differential cascode structure provides a virtual ground for odd harmonics (differential signals), but due to the bias network at the common node of the common source end of the cascode structure and the existence of the bonding gold wire, the two Even-order harmonics (common-mode signals) such as sub-harmonics are not completely terminated at low impedance, and will generate harmonic voltages at the resistance of the bias network and at the gold wire inductor, which will reduce linearity and affect overall performance.

Contents of the invention

The embodiment of the present invention provides a broadband differential radio frequency power amplifier with second harmonic suppression, which is used to solve the technical problem that the existing power amplifier has the second harmonic, which will reduce its linearity, work efficiency and output capability. A broadband differential RF power amplifier with second harmonic suppression can increase the bandwidth of the RF power amplifier.

In order to achieve the above purpose, embodiments of the present invention provide the following technical solutions:

A broadband differential radio frequency power amplifier with second harmonic suppression, comprising a broadband input balun, a driver amplifier, a T-shaped matching network, an output amplifier, a harmonic suppression matching network, and a broadband output balun;

The broadband input balun is used to convert a single-ended signal into a differential signal output to obtain an output signal;

The drive amplifier is connected to the output end of the broadband input balun and used to amplify the output signal;

The T-type matching network is arranged between the driving amplifier and the output amplifier and is used for matching impedance between the driving amplifier and the output amplifier;

The output amplifier is connected to the T-type matching network and used to output an amplified output signal;

The suppression harmonic matching network is connected to the output amplifier and used to suppress the second harmonic of the output signal;

The broadband output balun is connected with the suppression harmonic matching network and used to convert the suppressed output signal into a new single-ended signal output.

Preferably, the broadband input balun includes a high-pass filter and a low-pass filter connected in parallel with the high-pass filter, and the high-pass filter and the low-pass filter are connected in parallel to form out-of-phase power distribution of three connection ports The three connection ports are respectively an input connection port, a first differential output connection port and a second differential output connection port.

Preferably, both the high-pass filter and the low-pass filter are LCπ-type networks or LC T-type networks.

Preferably, the drive amplifier includes a first semiconductor element and a second semiconductor element connected in parallel with the first semiconductor element, the first end of the first semiconductor element is connected to the first differential output of the broadband input balun connected to the connection port, the first end of the second semiconductor element is connected to the second differential output connection port of the broadband input balun.

Preferably, the T-type matching network includes a first high-pass matching network and a second high-pass matching network, the first high-pass matching network includes a seventh capacitor, a fifth inductor and an eighth capacitor, and the second high-pass matching network includes The ninth capacitor, the fifth inductor and the tenth capacitor; the first high-pass matching network is connected to the second end of the first semiconductor element of the driving amplifier, and the second high-pass matching network is connected to the second semiconductor element of the driving amplifier The second end of the element is connected.

Preferably, the output amplifier includes a first output amplifier and a second output amplifier, the first output amplifier includes a third semiconductor element and a fourth semiconductor element, and the second output amplifier includes a fifth semiconductor element and a sixth semiconductor element element; the first end of the fourth semiconductor element is connected to the first high-pass matching network output end of the T-type matching network, and the first end of the fifth semiconductor element is connected to the second high-pass output end of the T-type matching network The output end of the matching network is connected, the third end of the third semiconductor element is connected to the second end of the fourth semiconductor element, the first end of the third semiconductor element is connected to the first end of the sixth semiconductor element connected, the third end of the third semiconductor element is used as the output end of the first output amplifier, the third end of the fifth semiconductor element is connected to the second end of the sixth semiconductor element, and the sixth The third terminal of the semiconductor element is used as the output terminal of the second output amplifier.

Preferably, a first LC series resonant network is connected in parallel between the first end of the third semiconductor element and the first end of the sixth semiconductor element.

Preferably, the harmonic suppression matching network includes two second LC series resonant networks, a seventh inductance and a fourteenth inductance connected in series with the two second LC series resonant networks, and two inductances connected in series with the two second LC series resonant networks. The sixteenth capacitor connected in parallel with two LC series resonant networks, the seventh inductance is connected to the first output amplifier output end of the output amplifier, and the fourteenth inductance is connected to the second output amplifier output end of the output amplifier .

Preferably, the second LC series resonant network includes a resonant capacitor and a resonant inductor, and the resonant capacitor is connected in series with the resonant inductor and grounded.

Preferably, the broadband output balun includes a first differential input connection end, a second differential input connection end, a high-pass output filter connected to the first differential input connection end, and a high-pass output filter connected to the second differential input connection end. A low-pass output filter, a DC blocking capacitor, and an output terminal connected to the DC blocking capacitor, the high-pass output filter is connected in parallel with the low-pass output filter and connected to the DC blocking capacitor, and the first A differential input connection end is connected to the second end of the seventh inductor of the harmonic suppression matching network, and the second differential input connection end is connected to the second end of the fourteenth inductor of the harmonic suppression matching network.

It can be seen from the above technical solutions that the embodiment of the present invention has the following advantages: the broadband differential radio frequency power amplifier with second harmonic suppression includes a broadband input balun, a driving amplifier, a T-shaped matching network, an output amplifier, and harmonic suppression matching Network and broadband output baluns. The broadband differential RF power amplifier with second harmonic suppression converts one single-ended signal into two differential output signals through a broadband input balun, and uses a drive amplifier, a T-shaped matching network, and an output amplifier to improve the power amplifier power of the output signal. After the output capability, use the harmonic suppression matching network to process the output signal with the second harmonic, which better reduces the influence of the second harmonic on the overall performance of the RF power amplifier, and improves performance indicators such as efficiency and linearity ; Also through the two-way synthesis of the output signal and one signal output in the broadband output balun; the broadband differential RF power amplifier with second harmonic suppression realizes the combination of harmonic suppression network and broadband balun, which improves the working bandwidth of the power amplifier ; Solve the technical problem that the existing power amplifier has the second harmonic, which will reduce its linearity, work efficiency and output capability.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained according to these drawings on the premise of not paying creative efforts.

FIG. 1 is a block diagram of a broadband differential radio frequency power amplifier with second harmonic suppression according to an embodiment of the present invention.

Fig. 2 is a circuit diagram of a broadband differential radio frequency power amplifier with second harmonic suppression according to an embodiment of the present invention.

Fig. 3a is a schematic circuit diagram of a wideband differential radio frequency power amplifier with second harmonic suppression and a wideband input balun LCπ network according to an embodiment of the present invention.

Fig. 3b is a schematic circuit diagram of an equivalent conversion between a broadband input balun π-type network and a T-type network of a broadband differential radio frequency power amplifier with second harmonic suppression according to an embodiment of the present invention.

Fig. 3c is a schematic circuit diagram of a wideband input balun composed of a π-type high-pass network and a T-type low-pass network for a wideband differential radio frequency power amplifier with second harmonic suppression according to an embodiment of the present invention.

Fig. 3d is a schematic circuit diagram of a broadband input balun composed of two multi-order filters of a broadband differential radio frequency power amplifier with second harmonic suppression according to an embodiment of the present invention.

Fig. 3e is a simulation effect diagram of a broadband input balun of a broadband differential radio frequency power amplifier with second harmonic suppression according to an embodiment of the present invention.

Fig. 4 is a harmonic processing framework diagram of a broadband differential radio frequency power amplifier with second harmonic suppression according to an embodiment of the present invention.

FIG. 5 is a circuit diagram of a harmonic suppression matching network and a broadband output balun of a broadband differential radio frequency power amplifier with second harmonic suppression according to an embodiment of the present invention.

FIG. 6 is a circuit block diagram of a harmonic suppression matching network of a broadband differential radio frequency power amplifier with second harmonic suppression according to an embodiment of the present invention.

FIG. 7 is a signal diagram of a harmonic-suppressed broadband differential radio frequency power amplifier according to an embodiment of the present invention after harmonic suppression.

Detailed ways

In order to make the purpose, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the following The described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The embodiment of the present application provides a broadband differential radio frequency power amplifier with second harmonic suppression, which is used to solve the technical problem that the existing power amplifier has a second harmonic, which will reduce its linearity, work efficiency and output capability. The broadband differential radio frequency power amplifier with second harmonic suppression can improve the bandwidth of the radio frequency power amplifier.

Embodiment one:

FIG. 1 is a block diagram of a broadband differential radio frequency power amplifier with second harmonic suppression according to an embodiment of the present invention.

As shown in Figure 1, the embodiment of the present invention provides a broadband differential RF power amplifier with second harmonic suppression, including a broadband input balun 10, a driver amplifier 20 connected to the broadband input balun 10, and a driver amplifier 20 The connected T-type matching network 30 , the output amplifier 40 connected with the T-type matching network 30 , the suppression harmonic matching network 50 connected with the output amplifier 40 and the broadband output balun 60 connected with the suppression harmonic matching network 50 .

In the embodiment of the present invention, the broadband input balun 10 is mainly used to convert one single-ended signal input to the radio frequency power amplifier into two differential signal outputs to obtain an output signal.

It should be noted that the broadband input balun 10 is provided with one input connection port and two differential output connection ports, and the two differential output connection ports are respectively denoted as a first differential output connection port and a second differential output connection port.

In the embodiment of the present invention, the driving amplifier 20 mainly amplifies the differential signals of the two outputs, so that the output signals can drive the operation of the output amplifier 40 .

It should be noted that the drive amplifier 20 adopts a cascode transistor structure to further improve the load capacity and output power of the power amplifier.

In the embodiment of the present invention, the T-shaped matching network 30 is mainly used to match corresponding impedances between the driving amplifier 20 and the output amplifier 40 .

In the embodiment of the present invention, the output amplifier 40 is mainly used to output a higher power differential signal.

It should be noted that the output amplifier 40 is to further improve the power output capability, and adopts a cascode structure.

In the embodiment of the present invention, the harmonic suppression matching network 50 is mainly used to suppress the second harmonic in the output signal.

It should be noted that the suppression harmonic matching network 50 uses two identical LC series resonant networks to be short-circuited to ground, which suppresses the second harmonic component in the output signal, reduces the influence of intermodulation products, and improves the RF power amplifier. work efficiency and linearity.

In the embodiment of the present invention, the broadband output balun 60 mainly converts two differential output signals into one single-ended output signal.

A broadband differential radio frequency power amplifier with second harmonic suppression provided by the present invention includes a broadband input balun, a drive amplifier, a T-shaped matching network, an output amplifier, a harmonic suppression matching network and a broadband output balun. The broadband differential RF power amplifier with second harmonic suppression converts one single-ended signal into two differential output signals through a broadband input balun, and uses a drive amplifier, a T-shaped matching network, and an output amplifier to improve the power amplifier power of the output signal. After the output capability, use the harmonic suppression matching network to process the output signal with the second harmonic, which better reduces the influence of the second harmonic on the overall performance of the RF power amplifier, and improves performance indicators such as efficiency and linearity ; Also through the two-way synthesis of the output signal and one signal output in the broadband output balun; the broadband differential RF power amplifier with second harmonic suppression realizes the combination of harmonic suppression network and broadband balun, which improves the working bandwidth of the power amplifier ; Solve the technical problem that the existing power amplifier has the second harmonic, which will reduce its linearity, work efficiency and output capability.

Fig. 2 is the circuit diagram of the broadband differential radio frequency power amplifier with second harmonic suppression described in the embodiment of the present invention, and Fig. 3 a is the broadband input bar of the broadband differential radio frequency power amplifier with second harmonic suppression described in the embodiment of the present invention The schematic circuit diagram of the Lun LCπ-type network, Fig. 3b is the circuit schematic diagram of the broadband differential RF power amplifier broadband input Balun π-type network and T-type network equivalent conversion with second harmonic suppression described in the embodiment of the present invention, Fig. 3c is the circuit principle diagram of the wideband input balun that the wideband differential radio frequency power amplifier with second harmonic suppression described in the embodiment of the present invention is composed of π-type high-pass network and T-type low-pass network, and Fig. 3d is this The circuit schematic diagram of the broadband input balun composed of two multi-order filters of the wideband differential radio frequency power amplifier with second harmonic suppression described in the embodiment of the invention, Fig. 3e is the second harmonic suppression described in the embodiment of the present invention. Simulation rendering of a wideband input balun for a wideband differential RF power amplifier with harmonic suppression.

As shown in Figures 2 to 3d, in one embodiment of the present invention, the broadband input balun 10 includes a high-pass filter and a low-pass filter connected in parallel with the high-pass filter, and the high-pass filter and the low-pass filter are connected in parallel to form three Out-of-phase power divider for connecting ports.

As shown in Figure 3a, in the embodiment of the present invention, both the high-pass filter and the low-pass filter are LCπ-type networks, and the high-pass filter includes a first capacitor connected in series with the input connection port 1 and at least two capacitors connected in parallel with the first capacitor The first inductor; the low-pass filter includes at least one second inductor connected in series with the input connection port 1 and at least two second capacitors C2 connected in parallel with the second inductor.

It should be noted that when the single-ended signal is transmitted from the input connection port 1 through the high-pass filter, a leading phase is generated, and when the single-ended signal is transmitted through the low-pass filter, a lagging phase is generated. The combination of the two is thus Realize the phase shift function of the broadband input balun 10. The high-pass filter or low-pass filter is equivalent to a π-type matching network, when the characteristic impedance Z0 of the high-pass filter or low-pass filter is equal to the input connection port 1 and the first differential output connection port 2 or the input connection port 1 and the second differential output connection port When the geometric mean value of the impedance between the two differential output connection ports 3, the input connection port 1 and the first differential output connection port 2 or the input connection port 1 and the second differential output connection port 3 pass through the corresponding high-pass filter or low-pass filter The device obtains good impedance matching, thereby realizing the impedance matching function of the broadband input balun 10. Therefore, the broadband input balun 10 composed of a high-pass filter and a low-pass filter can realize single-ended signal to differential signal conversion, and provide impedance matching between the differential end and the single-end.

As shown in Figure 3b, in the embodiment of the present invention, the LC π-type network conversion LC T-type network in the high-pass filter or low-pass filter mainly uses the equivalent conversion of the π-type network of two inductors and a capacitor to use A T-shaped circuit with one inductor and two capacitors.

As shown in Figure 3c, in the embodiment of the present invention, the high-pass filter is an LCπ-type network, and the low-pass filter is an LC T-type network as a case illustration. The broadband input composed of an LCπ-type network and an LC T-type network The balun 10 has the same characteristics and functions as the broadband input balun 10 shown in Figure 3a, but the number of inductors is reduced, because the area occupied by inductors in the chip is often much larger than that of capacitors, so the bandwidth is effectively reduced Enter the area occupied by balun 10. The broadband input balun 10 in this embodiment provides impedance matching between the balanced side and the unbalanced side, and at the same time provides conversion of single-ended signals to differential signals. By adjusting the position and direction of the broadband input balun 10, the broadband input balun 10 Placed at the signal input end as a power splitter, and placed as a power combiner.

As shown in Figure 3d, in the embodiment of the present invention, according to the requirements of the design index, the bandwidth of the amplitude balance of the broadband input balun 10 can be improved by increasing the order of the filter, with two 3rd-order high-pass filters and/or The low-pass filters are combined into one 5th-order high-pass filter and/or low-pass filter. As an example, two identical 3rd-order high-pass filters or two identical 3rd-order low-pass filters are The same components are equivalently replaced by one component to form a 5th-order high-pass filter or a 5th-order low-pass filter. Among them, each 3rd-order high-pass filter or low-pass filter achieves a phase shift leading (or lagging) by 45°, thereby realizing a 5th-order high-pass filter or low-pass filter to achieve a phase shift leading/lag of 90° The simulation results are shown in FIG. 3e, and the results show that the wideband input balun 10 obtains good bandwidth and good phase error.

As shown in FIG. 2 , the broadband input balun 10 uses a high-pass filter and a low-pass filter of a 5th-order LCπ network as an example for illustration. Among them, the high-pass filter of the 5th-order LCπ network is composed of capacitor C1, inductor L1, capacitor C2, inductor L2, and capacitor C3, and the low-pass filter of the 5th-order LCπ network is composed of capacitor C4, inductor L3, capacitor C5, and inductor L4. , Capacitor C6 composition. The high-pass filter of the 5th-order LCπ-type network and the low-pass filter of the 5th-order LCπ-type network together form a power divider, which is used to provide impedance matching between the balanced side and the unbalanced side, and at the same time, the input from the input connection port 1 Convert single-ended signals to differential signals.

As shown in FIG. 2, in one embodiment of the present invention, the driving amplifier 20 includes a first semiconductor element M1 and a second semiconductor element M2 connected in parallel with the first semiconductor element M1, the first end of the first semiconductor element M1 is connected to The broadband input balun 10 is connected to the first differential output connection port 2 , and the first end of the second semiconductor element M2 is connected to the second differential output connection port 3 of the broadband input balun 10 . Wherein, the third end of the first semiconductor element M1 is connected to the third end of the second semiconductor element M2 and then grounded.

It should be noted that the first end of the first semiconductor element M1 is respectively connected to the capacitor C3 and the bias circuit, the first end of the second semiconductor element M2 is respectively connected to the capacitor C6, the inductor L4 and the bias circuit, the first semiconductor element Both the second terminal of M1 and the second terminal of the second semiconductor element M2 are connected to the T-shaped matching network 30 . Both the first semiconductor element M1 and the second semiconductor element M2 are preferably selected as transistors, and in other embodiments, both the first semiconductor element M1 and the second semiconductor element M2 may be semiconductor elements with a function of increasing power. In this embodiment, the gate of the transistor is the first terminal, the source of the transistor is the second terminal, and the drain of the transistor is the third terminal. The common source amplifier composed of the first semiconductor element M1 and the second semiconductor element M2 is used as a driving amplifier to provide driving power and certain amplification for the output amplifier.

As shown in Figure 2, in one embodiment of the present invention, the T-type matching network 30 includes a first high-pass matching network and a second high-pass matching network, and the first high-pass matching network includes a seventh capacitor C7, a fifth inductor L5 and a fifth capacitor C7. Eight capacitors C8, the second high-pass matching network includes the ninth capacitor C9, the fifth inductance L5 and the tenth capacitor C10, the first high-pass matching network is connected to the second end of the first semiconductor element M1 of the drive amplifier 20, the second high-pass matching network It is connected with the second end of the second semiconductor element M2 of the driving amplifier 20 . Wherein, the first terminal of the seventh capacitor C7 is connected to the second terminal of the first semiconductor element M1, and the second terminal of the seventh capacitor C7 is respectively connected to the first terminal of the fifth inductor L5 and the first terminal of the eighth capacitor C8. , the second end of the eighth capacitor C8 is connected to the output amplifier 40; the first end of the ninth capacitor C9 is connected to the second end of the second semiconductor element M2, and the second end of the ninth capacitor C9 is respectively connected to the fifth inductor L5 The second end is connected to the first end of the tenth capacitor C10 , and the second end of the tenth capacitor C10 is connected to the output amplifier 40 .

It should be noted that the first high-pass matching network and the second high-pass matching network are respectively used for impedance matching between the upper and lower driving amplifiers 20 and the output amplifier 40 . Among them, the two parallel-connected ground inductors in the first high-pass matching network and the second high-pass matching network are directly connected to the common ground, and the intersection point is an AC virtual ground, and the equivalent inductance after omitting the physical ground is the fifth inductor L5.

As shown in Figure 2, in one embodiment of the present invention, the output amplifier 40 includes a first output amplifier and a second output amplifier, the first output amplifier includes a third semiconductor element M3 and a fourth semiconductor element M4, and the second output amplifier Including the fifth semiconductor element M5 and the sixth semiconductor element M6; the first end of the fourth semiconductor element M4 is connected to the first high-pass matching network output end of the T-type matching network 30, and the first end of the fifth semiconductor element M5 is connected to the T-type The second high-pass matching network output end of the matching network 30 is connected, the third end of the third semiconductor element M3 is connected to the second end of the fourth semiconductor element M4, the first end of the third semiconductor element M3 is connected to the sixth semiconductor element M6 The first end is connected, the third end of the third semiconductor element M3 is used as the output end of the first output amplifier, the third end of the fifth semiconductor element M5 is connected to the second end of the sixth semiconductor element M6, and the third end of the sixth semiconductor element M6 is connected to the second end of the sixth semiconductor element M6. The third end serves as the output end of the second output amplifier.

It should be noted that the output amplifier 40 is an output stage, and in order to further improve the power output capability, the output stage adopts a cascode structure. The third semiconductor element M3 and the fourth semiconductor element M4 are respectively the common-gate transistor and the common-source transistor of the first output amplifier, and the fifth semiconductor element M5 and the sixth semiconductor element M6 are respectively the common-source transistor and the common-source transistor of the second output amplifier. The source terminals of the two common source tubes are shorted, and the differential signal is radio frequency virtual ground at the common node, which can reduce the degradation effect caused by the source gold wire of the common source semiconductor element. Compared with the existing common-source structure power amplifier, the power amplifier of the cascode structure of the output amplifier 40 has higher output impedance, and higher amplification, and reduces the influence of the Miller capacitance, so that it has a higher reverse isolation. In addition, the cascode structure of the output amplifier 40 doubles the maximum withstand voltage between the drain and source of the transistor to increase the breakdown voltage for higher output power. In this embodiment, the third semiconductor element M3, the fourth semiconductor element M4, the fifth semiconductor element M5 and the sixth semiconductor element M6 are all preferably selected as transistors. In other embodiments, the third semiconductor element M3, the fourth semiconductor element The element M4, the fifth semiconductor element M5 and the sixth semiconductor element M6 can all be semiconductor elements with a function of increasing power. In this embodiment, the gate of the transistor is the first terminal, the source of the transistor is the second terminal, and the drain of the transistor is the third terminal.

As shown in FIG. 2 , in the embodiment of the present invention, a first LC series resonant network is connected in parallel between the first end of the third semiconductor element M3 and the first end of the sixth semiconductor element M6 .

Fig. 4 is a harmonic processing framework diagram of a broadband differential radio frequency power amplifier with second harmonic suppression according to an embodiment of the present invention.

It should be noted that the first LC series resonant network includes an eleventh capacitor C11 and a sixth inductor L6, and the resonant frequency of the first LC series resonant network is the second harmonic frequency. One end of the T-shaped matching network is connected to the common node between the first end of the fourth semiconductor element M4 and the first end of the fifth semiconductor element M5, and the purpose is to short-circuit the second harmonic at the common node to the ground. As shown in FIG. 4, since the signal input to the output amplifier 40 is a differential signal, its odd harmonic component is also a differential signal, so the odd harmonic component is transmitted between the fourth semiconductor element M4 and the fifth semiconductor element M5 of the common gate transistor. The common node of is a virtual ground, and the gate-source voltage at the odd harmonic frequency at this node is 0. Since the bias circuit includes resistors and bonding gold wires, for even harmonic components, the impedance at the common node is not zero, which will cause additional loss and nonlinear effects. Therefore, by adding a first LC series resonant network whose resonant frequency is the second harmonic frequency at the common node of the third semiconductor element M3 and the fourth semiconductor element M4 of the common gate tube, the two most influential even harmonics The subharmonic components are shorted to ground to reduce mixing of second-order products in intermodulation distortion, thereby improving linearity.

FIG. 5 is a circuit diagram of a harmonic suppression matching network and a broadband output balun of a broadband differential radio frequency power amplifier with second harmonic suppression according to an embodiment of the present invention.

As shown in Figures 2 and 5, in one embodiment of the present invention, the suppressing harmonic matching network 50 includes two second LC series resonant networks, a seventh inductance L7 connected in series with the two second LC series resonant networks respectively and the fourteenth inductance L14, and the sixteenth capacitor 16 connected in parallel with the two second LC series resonant networks, the first end of the seventh inductance L7 is connected with the first output amplifier output end of the output amplifier 40, the fourteenth inductance The first end of L14 is connected to the second output amplifier output end of the output amplifier 40 . Wherein, the second LC series resonant network includes a resonant capacitor and a resonant inductor, and the resonant capacitor and the resonant inductor are connected in series and grounded. Both the second end of the seventh inductor L7 and the second end of the fourteenth inductor L14 are connected to the broadband output balun 60 .

It should be noted that, as shown in Figure 2 and Figure 5, a second LC series resonant network uses capacitor C12 as the resonant capacitor and inductor L12 as the resonant inductance; another second LC series resonant network uses capacitor C17 as the resonant capacitor, inductor L11 acts as a resonant inductor. Two identical second LC series resonant networks whose resonant frequency is at the second harmonic frequency are respectively connected to the drain of the third semiconductor element M3 and the drain of the sixth semiconductor element M6 of the common gate transistor of the output amplifier 50. It is to short-circuit the second harmonic in the output signal of the drain of the third semiconductor element M3 and the drain of the sixth semiconductor element M6 to the ground, thereby suppressing the second harmonic with the largest component among the even harmonics from affecting the power amplifier. performance impact.

FIG. 6 is a circuit block diagram of a harmonic suppression matching network of a broadband differential radio frequency power amplifier with second harmonic suppression according to an embodiment of the present invention.

In the embodiment of the present invention, the second LC series resonant network resonating at the second harmonic frequency presents a capacitive reactance to the fundamental frequency, which is equivalent to a capacitor, and the two second LC series resonant networks are respectively connected in series with the seventh inductor L7 and the sixteenth capacitor C16 in parallel, the fourteenth inductance L14 in series and the sixteenth capacitor C16 in parallel form a π-type low-pass matching network, which matches the load line impedance of the transistor to an intermediate impedance Za, etc. The effective circuit is shown in Figure 6. Among them, the sixteenth capacitor C16 is directly connected to the common ground of two parallel capacitors in two π-type low-pass matching networks, and the intersection point presents an AC virtual ground. The capacitance value of sixteen capacitors C16 is half of the capacitance value of a single parallel capacitor in the π-type low-pass matching network.

As shown in Figure 2 and Figure 5, in one embodiment of the present invention, the broadband output balun 60 includes a first differential input connection end, a second differential input connection end, a high-pass output filter connected to the first differential input connection end device, a low-pass output filter connected to the second differential input connection end, a DC blocking capacitor C21, and an output connection end connected to the DC blocking capacitor C21, and the high-pass output filter and the low-pass output filter are connected in parallel with the DC blocking capacitor C21 connection, the first differential input connection end is connected to the second end of the seventh inductor L7, and the second differential input connection end is connected to the second end of the fourteenth inductor L14.

FIG. 7 is a signal diagram of a harmonic-suppressed broadband differential radio frequency power amplifier according to an embodiment of the present invention after harmonic suppression.

It should be noted that, as shown in Figure 2 and Figure 5, capacitor C13, inductor L8, capacitor C14, inductor L9, and capacitor C15 form a 5th-order low-pass output filter, and capacitor C18, inductor L12, capacitor C19, inductor L13, Capacitor C20 forms a 5th-order high-pass output filter, which has the same principle and structure as the broadband input balun 10, and the port direction is opposite. The high-pass output filter and the low-pass output filter form a power combiner to convert two differential signals into single-ended signal while matching the impedance from the intermediate impedance Za to the load impedance of 50 ohms. In this embodiment, a 5th-order high-pass output filter and a low-pass output filter structure are used to realize a broadband output balun. The filter order can be adjusted according to the bandwidth requirements and simulation results, but if the filter order is too high, it will Affects the phase balance, and needs to be considered in design. A DC blocking capacitor C21 is used to filter out the DC signal in the output signal. The selection of the intermediate impedance Za can be adjusted according to the design bandwidth and the simulation results. Usually, the geometric mean value of the load line impedance and the load impedance (50 ohms) is used to obtain a better bandwidth. The specific design can be based on the simulation around this value. The results are adjusted. As shown in FIG. 7 , the output signal of the broadband differential radio frequency power amplifier with second harmonic suppression has a good suppression effect on the second harmonic and has a good bandwidth.

In the wideband differential radio frequency power amplifier with second harmonic suppression of the present invention, it has the following advantages:

One is the broadband balun structure realized by using the phase shifting and impedance matching functions of the filter, and it is given to adjust the structure of the broadband balun according to the bandwidth requirements. The method improves the bandwidth under the premise of maintaining the 180° phase difference at the differential end of the broadband balun. The broadband balun proposed by the present invention can also be extended to be combined with a common two-element L-shaped matching network, and greater design flexibility can be obtained by selecting the impedance between the broadband balun and the L-shaped matching network. In this example, only the broadband balun composed of the 5th order filter and the broadband balun composed of the 3rd order filter are respectively used as the power divider and the power combiner of the differential structure power amplifier, but it is not limited thereto.

The second is to adopt the output amplifier with cascode transistor structure to further improve the load capacity and output power of the differential power amplifier, and connect the first LC series resonant network in parallel at the common node of the differential cascode transistor to realize the protection of the second harmonic processing, the first LC series resonant network shorts the second harmonic of the differential cascode transistors at the common node to ground to reduce the impact of the second harmonic on this wideband differential RF power amplifier with second harmonic suppression .

The third is the suppression harmonic matching network with the second harmonic suppression function applied to the differential structure power amplifier, the equivalent capacitance of the second harmonic short-circuit circuit at the fundamental frequency of the two second LC series resonant networks and the broadband output bar Lun's two-way L-type matching network is combined to form a π-type matching network with a differential structure. Wherein, the parallel elements in the two L-shaped matching networks are directly connected to the common ground, and the intersection point presents an AC virtual ground, thereby omitting physical grounding, and further saving the area of the broadband differential RF power amplifier with second harmonic suppression.

The fourth is to improve the overall performance of the broadband differential radio frequency power amplifier with second harmonic suppression through the combination of broadband input balun, output amplifier, harmonic suppression matching network and broadband output balun.

Compared with the existing classic four-element LC balun, which consists of two L-shaped matching networks, the element parameters are only determined by the frequency and impedance transformation ratio, and the element parameters cannot be adjusted and the bandwidth is narrow. A broadband differential radio frequency power amplifier with second harmonic suppression proposed by the present invention is based on a lumped element balun structure. Compared with the classic LC balun, the broadband differential radio frequency power amplifier with second harmonic suppression The wideband balun can obtain better bandwidth and design flexibility by adjusting the phase shift and characteristic impedance of the two-way filters. At the same time, considering the actual engineering design layout, compared with the classic four-element LC balun, several elements have been added, but the number of inductors has been reduced as much as possible, so the chip area occupied by the balun structure proposed by the present invention There is no significant increase and does not complicate the layout design.

The broadband differential radio frequency power amplifier with second harmonic suppression of the present invention adopts the output amplifier of the cascode transistor structure to improve the power output capability of the power amplifier; and adopts the second harmonic at the common node of the common gate tube An LC series resonant network is used for processing, which can better reduce the influence of the second harmonic on the overall performance of the power amplifier, and improve performance indicators such as efficiency and linearity. By introducing a second LC series resonant network into the harmonic suppression matching network and broadband output balun, the second harmonics in the two output signals are short-circuited to ground through two identical second LC series resonant networks, which suppresses The second harmonic component in the output signal reduces the influence of intermodulation products and improves efficiency and linearity. In addition, the broadband differential radio frequency power amplifier with second harmonic suppression realizes the combination of harmonic suppression network and broadband balun, thereby improving the working bandwidth of the broadband differential radio frequency power amplifier with second harmonic suppression.

The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be described in the foregoing embodiments Modifications are made to the recorded technical solutions, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (9)

1. A broadband differential radio frequency power amplifier with second harmonic suppression is characterized by comprising a broadband input balun, a drive amplifier, a T-shaped matching network, an output amplifier, a harmonic suppression matching network and a broadband output balun;

the broadband input balun is used for converting the single-end signal into a differential signal to be output so as to obtain an output signal;

the driving amplifier is connected with the output end of the broadband input balun and is used for amplifying the output signal;

the T-shaped matching network is arranged between the driving amplifier and the output amplifier and is used for matching impedance between the driving amplifier and the output amplifier;

the output amplifier is connected with the T-shaped matching network and is used for outputting an amplified output signal;

the harmonic suppression matching network is connected with the output amplifier and is used for suppressing the second harmonic of the output signal;

the broadband output balun is connected with the harmonic suppression matching network and is used for converting the suppressed output signal into a new single-ended signal to be output;

the output amplifier includes a first output amplifier including a third semiconductor element and a fourth semiconductor element, and a second output amplifier including a fifth semiconductor element and a sixth semiconductor element; a first end of the fourth semiconductor element is connected with an output end of a first high-pass matching network of the T-type matching network, a first end of the fifth semiconductor element is connected with an output end of a second high-pass matching network of the T-type matching network, a third end of the third semiconductor element is connected with a second end of the fourth semiconductor element, a first end of the third semiconductor element is connected with a first end of the sixth semiconductor element, a third end of the third semiconductor element is used as an output end of the first output amplifier, a third end of the fifth semiconductor element is connected with a second end of the sixth semiconductor element, and a third end of the sixth semiconductor element is used as an output end of the second output amplifier.

2. The wideband differential rf power amplifier with second harmonic suppression as claimed in claim 1 wherein the wideband input balun includes a high pass filter and a low pass filter in parallel with the high pass filter, the high pass filter and the low pass filter in parallel forming an out of phase power splitter with three connection ports, the three connection ports being an input connection port, a first differential output connection port and a second differential output connection port respectively.

3. The wideband differential radio frequency power amplifier with second harmonic suppression as claimed in claim 2, characterized by the high pass filter and the low pass filter being both LC pi or LC T type networks.

4. The wideband differential radio frequency power amplifier with second harmonic suppression of claim 1, wherein the driver amplifier comprises a first semiconductor element and a second semiconductor element connected in parallel with the first semiconductor element, a first end of the first semiconductor element being connected to a first differential output connection port of the wideband input balun and a first end of the second semiconductor element being connected to a second differential output connection port of the wideband input balun.

5. The wideband differential radio frequency power amplifier with second harmonic suppression of claim 1, wherein the T-type matching network comprises a first high-pass matching network and a second high-pass matching network, the first high-pass matching network comprising a seventh capacitance, a fifth inductance, and an eighth capacitance, the second high-pass matching network comprising a ninth capacitance, a fifth inductance, and a tenth capacitance; the first high-pass matching network is connected with the second end of the first semiconductor element of the driving amplifier, and the second high-pass matching network is connected with the second end of the second semiconductor element of the driving amplifier; a first end of the seventh capacitor is connected to the second end of the first semiconductor element, a second end of the seventh capacitor is connected to the first end of the fifth inductor and the first end of the eighth capacitor, and a second end of the eighth capacitor is connected to the output amplifier; a first end of the ninth capacitor is connected to the second end of the second semiconductor element, a second end of the ninth capacitor is connected to the second end of the fifth inductor and the first end of the tenth capacitor, respectively, and a second end of the tenth capacitor is connected to the output amplifier.

6. The wideband differential radio frequency power amplifier with second harmonic suppression as claimed in claim 1, further having a first LC series resonant network connected in parallel between the first end of the third semiconductor element and the first end connection of the sixth semiconductor element.

7. The wideband differential rf power amplifier with second harmonic suppression of claim 1, wherein the harmonic suppression matching network comprises two second LC series resonant networks, a seventh inductor and a fourteenth inductor connected in series with the two second LC series resonant networks, respectively, and a sixteenth capacitor connected in parallel with the two second LC series resonant networks, the seventh inductor being connected to the first output amplifier output of the output amplifier, the fourteenth inductor being connected to the second output amplifier output of the output amplifier; a first end of the second LC series resonant network is connected with the seventh inductor, and a second end of the second LC series resonant network is grounded; the first end of the other second LC series resonant network is connected to the fourteenth inductor, and the second end of the second LC series resonant network is grounded.

8. The wideband differential radio frequency power amplifier with second harmonic suppression of claim 7, wherein the second LC series resonant network comprises a resonant capacitor and a resonant inductor, the resonant capacitor being connected in series with the resonant inductor and then connected to ground.

9. The wideband differential rf power amplifier with second harmonic suppression according to claim 1, wherein the wideband output balun includes a first differential input connection terminal, a second differential input connection terminal, a high-pass output filter connected to the first differential input connection terminal, a low-pass output filter connected to the second differential input connection terminal, a dc blocking capacitor, and an output connection terminal connected to the dc blocking capacitor, the high-pass output filter is connected to the dc blocking capacitor after being connected to the low-pass output filter in parallel, the first differential input connection terminal is connected to a seventh inductive second terminal of the harmonic suppression matching network, and the second differential input connection terminal is connected to a fourteenth inductive second terminal of the harmonic suppression matching network.

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