CN111934629A - Broadband high-linearity power amplifier - Google Patents

Abstract

The invention discloses a broadband high linearity power amplifier, comprising an input matching network, a first-stage driving amplifier 100, a first-stage inter-stage matching network, a second-stage driving amplifier 200, a second-stage inter-stage matching network, an output matching network connected in sequence The stage power amplifier 300 and the output matching network, the first stage driver amplifier 100, the second stage driver amplifier 200 and the output stage power amplifier 300 all include left and right symmetrical differential capacitor neutralizing amplifiers and second harmonic short circuits. Through the above method, the present invention can improve the amplitude linearity and phase linearity of the power amplifier, suppress the third-order intermodulation amount, enhance the ability of the power amplifier to transmit high-power broadband high-order modulation signals, and on the other hand, suppress the common mode interference The influence of the signal enhances the reliability of the power amplifier and improves the overall working ability of the power amplifier at high frequencies.

Description

A Broadband High Linearity Power Amplifier

technical field

The invention relates to the technical field of electronic circuit design, in particular to a broadband high linearity power amplifier.

Background technique

In recent years, the new generation of communication technology has achieved rapid development, and the communication based on the sub-6GHz frequency band can no longer meet the growing demand for bandwidth. Therefore, high-frequency communication based on 6GHz or above, such as millimeter-wave 5G communication, broadband satellite communication, etc. direction of development. Small-sized devices used in high-frequency communication make large-scale phased array technology possible. This technology can effectively compensate for the high loss of high-frequency communication and improve the coverage of high-frequency communication, so it is widely used in high-frequency communication systems. Through multi-antenna array and beamforming technology, large-scale phased array system can achieve higher output power to overcome propagation loss; at the same time, the beam direction can be adjusted according to the real-time needs of users to provide flexible signal coverage. Large-scale phased array systems combined with broadband high-order modulation signals (eg, 64-QAM, 256-QAM) can realize ultra-high-speed, low-latency wireless communications. However, compared with the constant envelope signal (for example, QPSK), the broadband high-order modulation signal has higher requirements on the amplitude linearity and phase linearity of the system; at the same time, the extremely high peak-to-average ratio of the broadband high-order modulation signal also affects the The linearity of large-scale phased array systems presents challenges.

The power amplifier is located at the antenna end of each array element of the large-scale phased array system. It is the main source of nonlinear characteristics of the entire system, and it is also the bottleneck for the entire system to transmit broadband high-order modulation signals. The existing power amplifier generally adopts the differential capacitor neutralization amplifier structure with class AB bias. Class AB PAs offer higher efficiency and a 1dB compression point near saturation output power compared to Class A PAs; while differential capacitor neutralizing amplifiers offer higher gain at high frequencies (e.g., mmWave bands) and good stability, therefore, class AB biased differential capacitor neutralizing amplifiers are widely used to transmit constant envelope signals. However, the differential capacitor neutralization amplifier under class AB bias will generate a large number of second harmonics, which will deteriorate the amplitude linearity, phase linearity and third-order intermodulation of the power amplifier, and seriously affect the transmission of broadband high-order modulation signals. . Therefore, the class AB biased differential capacitor neutralizing amplifier still needs to be improved to make it suitable for large-scale phased array systems transmitting broadband high-order modulated signals. The invention introduces a second harmonic short circuit on the basis of the capacitor and amplifier in the AB class bias differential, suppresses a large number of second harmonics generated by the differential capacitor neutralization amplifier under the AB class bias, and improves the amplitude linearity and the power amplifier. Phase linearity, suppressing third-order intermodulation, making the power amplifier suitable for transmitting broadband high-order modulation signals.

SUMMARY OF THE INVENTION

The purpose of the invention is to provide a broadband high linearity power amplifier, which can improve the amplitude linearity and phase linearity of the power amplifier, suppress the third-order intermodulation, and enhance the power amplifier's ability to transmit high-power broadband high-order modulation signals. On the other hand, the influence of the common mode interference signal is suppressed, the reliability of the power amplifier is enhanced, and the working capability of the power amplifier at high frequencies is improved as a whole.

In order to solve the above-mentioned technical problems, a technical solution adopted by the present invention is to provide a broadband high linearity power amplifier, which is characterized in that it includes an input matching network, a first-stage driving amplifier, a first inter-stage matching network, a A two-stage driving amplifier, a second-stage inter-stage matching network, an output-stage power amplifier and an output-stage matching network, the first-stage driving amplifier, the second-stage driving amplifier and the output-stage power amplifier all include left-right symmetrically arranged differential capacitance neutralization Amplifier and second harmonic short circuit.

Further, the input matching network, the first inter-stage matching network, the second inter-stage matching network and the output matching network are respectively an input matching transformer, a first inter-stage matching transformer, a second inter-stage matching transformer and an output matching transformer. The transformers are all on-chip integrated transformers, which are realized by overlapping inductive coils composed of different metal layers.

Further, the input matching transformer, the first inter-stage matching transformer and the second inter-stage matching transformer are realized in the form of weakly coupled transformers, and the output matching transformer is realized in the form of strong coupling transformers, wherein: the first inter-stage matching transformer, the third The inter-stage matching transformer and the output matching transformer respectively provide DC power for the first driving stage amplifier, the second driving stage amplifier and the output stage power amplifier.

Further, the first-stage driving amplifier, the second-stage driving amplifier and the output-stage power amplifier have the same structure.

Further, the differential capacitance neutralizing amplifier of the first-stage driving amplifier is composed of a first transistor, a second transistor, a first capacitor and a second capacitor, and the device sizes of the first transistor and the second transistor are the same, so The first capacitor and the second capacitor are the same; the gate of the first transistor is connected in series with the first capacitor and then connected to the drain of the second transistor, and the gate of the second transistor is connected in series with the second capacitor and then connected to the first capacitor. On the drain of the transistor, the gate and drain of the first transistor and the second transistor are respectively connected to the differential signal path; the differential capacitance neutralization amplifier of the second-stage driver amplifier includes the third to fourth transistors and the third to fourth transistors. Five to six capacitors; the differential capacitor neutralization amplifier of the output stage power amplifier includes fifth to sixth transistors and ninth to tenth capacitors.

Further, the second harmonic short-circuit circuit of the first-stage driving amplifier is composed of a first inductor, a second inductor, a third capacitor and a fourth capacitor, the first inductor and the second inductor are the same, and the third capacitor and the third capacitor are the same. The four capacitors are the same; one end of the first inductor is connected to the source of the first transistor, the other end is connected to the source of the second transistor after being connected in series with the second inductor, one end of the third capacitor is connected to the drain of the first transistor, and the other end is connected to the source of the second transistor. One end of the fourth capacitor is connected in series with the drain of the second transistor, and the junction of the third capacitor and the fourth capacitor is connected to the junction of the first inductor and the second inductor; The sub-harmonic short circuit includes seventh to eighth capacitors and third to fourth inductors; the second harmonic short circuit of the output stage power amplifier includes eleventh to twelfth capacitors and fifth to sixth inductors.

Further, the device size of the differential capacitor neutralizing amplifier in the first-stage driving amplifier, the second-stage driving amplifier and the output-stage power amplifier is proportionally increased, wherein: the first to second transistors, the third to fourth transistors and The device size ratio of the fifth to sixth transistors is 2:3:4; the capacitance value ratio of the first to second capacitors, the fifth to sixth capacitors, and the ninth to tenth capacitors is 2:3:4.

Further, the device size of the second harmonic short circuit in the first-stage driving amplifier, the second-stage driving amplifier and the output-stage power amplifier is the same, and the inductance values of the first to sixth inductors are the same; The capacitance values of the capacitors, the seventh to eighth capacitors, and the eleventh to twelfth capacitors are the same.

Further, the input matching transformer forms an input matching network, the first inter-stage matching transformer and the third to fourth capacitors form a first inter-stage matching network, and the second inter-stage matching transformer and the seventh to eight capacitors form a second stage The output matching transformer and the eleventh to twelfth capacitors form the output matching network.

The beneficial effects of the present invention are: a broadband high linearity power amplifier of the present invention has the following advantages:

First, the present invention proposes a differential capacitor neutralization amplifier structure with a second harmonic short circuit. On the one hand, the amplitude linearity and phase linearity of the power amplifier are improved, the third-order intermodulation is suppressed, and the The ability of the power amplifier to transmit high-power broadband high-order modulation signals, on the other hand, suppresses the influence of common mode interference signals, enhances the reliability of the power amplifier, and improves the overall working ability of the power amplifier at high frequencies;

Second, the present invention suppresses the influence of the second harmonic on the modulated signal by combining the differential capacitor neutralizing amplifier and the second harmonic short circuit, thereby improving the amplitude linearity and phase linearity of the power amplifier at high frequencies;

Third, the capacitors in the second harmonic short circuit are absorbed in the matching network, which eliminates the effect of the second harmonic short circuit on the fundamental wave without affecting the amplitude linearity and phase linearity of the power amplifier at high frequencies. influence of the signal.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying 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 described in the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

1A is a schematic diagram of the circuit structure of a broadband high linearity power amplifier of the present invention;

1B is a schematic diagram of the circuit structure of the first-stage driver amplifier in the present invention in a common mode signal mode;

1C is a schematic diagram of the circuit structure of the first-stage driver amplifier in the present invention in a differential mode signal mode;

Fig. 2 is the result of gain and input and output reflection coefficient of a kind of broadband high linearity power amplifier of the present invention;

Fig. 3 is the result of output 1dB compression point and output 3dB compression point of a kind of broadband high linearity power amplifier of the present invention;

Fig. 4 is the result of the amplitude linearity of a kind of broadband high linearity power amplifier of the present invention;

Fig. 5 is the result of the phase linearity of a kind of broadband high linearity power amplifier of the present invention;

FIG. 6 is a third-order intermodulation (IMD3) result of a broadband high linearity power amplifier of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Examples of these preferred embodiments are illustrated in the accompanying drawings. The embodiments of the invention shown in the drawings and described with reference to the drawings are merely exemplary and the invention is not limited to these embodiments.

Here, it should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only the structures and/or processing steps closely related to the solution according to the present invention are shown in the drawings, and the related structures and/or processing steps are omitted. Other details not relevant to the invention.

And, in the description of the present invention, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate orientations Or the positional relationship is based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation. , so it should not be construed as a limitation of the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed to indicate or imply relative importance.

Referring to FIGS. 1 to 6, the embodiments of the present invention include: as shown in FIG. 1, the present invention provides a broadband high linearity power amplifier, including an input matching transformer 400, a first-stage driver amplifier 100, The first inter-stage matching transformer 401, the second-stage driving amplifier 200, the second inter-stage matching transformer 402, the output-stage power amplifier 300 and the output matching transformer 403, all of the amplifiers at each stage adopt a differential capacitor neutralization structure with There is a second harmonic short circuit. Compared with the existing power amplifier based on the differential capacitor neutralization amplifier, the broadband high linearity power amplifier provided by the present invention improves the amplitude linearity and phase linearity, suppresses the third-order intermodulation amount, and enhances the transmission bandwidth of the power amplifier. The performance of higher order modulated signals.

Based on the structure of the differential capacitor neutralizing amplifier, the present invention provides a structure suitable for improving the amplitude linearity and phase linearity of the differential power amplifier while suppressing the third-order intermodulation amount. FIG. 1A is a circuit of a broadband high linearity power amplifier. Schematic diagram of the structure, FIG. 1B is a schematic diagram of the circuit structure of the first-stage driving amplifier in FIG. 1A in the common mode signal mode, and FIG. 1C is a schematic diagram of the circuit structure of the first-stage driving amplifier in FIG. 1A in the differential mode signal mode. in particular:

The first-stage driver amplifier 100, the second-stage driver amplifier 200, and the output-stage driver amplifier 300 have the same structure. Taking the first-stage driving amplifier 100 as an example, the structure is composed of a differential capacitor neutralizing amplifier and a second harmonic short circuit. The differential capacitor neutralizing amplifier is composed of a transistor 101 , a transistor 102 , a capacitor 103 and a capacitor 104 . The device size of the transistor 101 is the same as that of the transistor 102 , and the capacitor 103 and the second capacitor 104 are the same. When the power amplifier is working, the capacitor 103 and the capacitor 104 can improve the gain and stability of the power amplifier. The second harmonic short circuit is composed of an inductor 105 , an inductor 106 , a capacitor 107 and a capacitor 108 . The inductor 105 is the same as the inductor 106 , and the capacitor 107 is the same as the fourth capacitor 108 . When the power amplifier is working, for common mode signals and even harmonics, the circuit structure is as shown in Figure 1B; transistor 101 and transistor 102 are connected in parallel, the gate, source and drain are connected to each other in turn, capacitor 103 and capacitor 104 After parallel connection, the two ends are connected to the gate and drain of transistor 101 and transistor 102 respectively; inductor 105, inductor 106, capacitor 107 and capacitor 108 form a series resonant circuit resonating at the second harmonic frequency, so that the second harmonic of the power amplifier The harmonic load is close to a short circuit, thereby suppressing the second harmonic and improving the amplitude linearity, phase linearity and third-order intermodulation of the power amplifier; for the differential mode fundamental signal and odd harmonics, the circuit structure is shown in Figure 1C As shown; transistor 101, transistor 102, capacitor 103 and capacitor 104 constitute a differential capacitor neutralizing amplifier; inductor 105 and inductor 106 are short-circuited to ground, which will not affect the differential mode fundamental signal and odd harmonics. The capacitor 107 and the capacitor 108 are connected in series to the drains of the transistor 101 and the transistor 102 in parallel, and will be absorbed in the matching network. The difference between the second-stage driver amplifier 200, the output-stage driver amplifier 300 and the first-stage driver amplifier is only in the size of the transistor and the specific value of the capacitance. The device size ratio of the transistor 101, the transistor 201 and the transistor 301 is 2:3:4; 101 and 102, transistors 201 and 202, and transistors 301 and 302 have the same size respectively; the capacitance ratio of capacitor 103, capacitor 203 and capacitor 303 is 2:3:4; capacitors 103 and 104, capacitors 203 and 204, capacitors 303 and 303 The capacitance values of 304 are respectively the same.

The input matching transformer 400 , the first inter-stage matching transformer 401 and the second inter-stage matching transformer 402 are implemented in the form of weakly coupled transformers, and the output matching transformer 403 is implemented in the form of strong coupling transformers. The first inter-stage matching transformer 401 , the second inter-stage matching transformer 402 and the output matching transformer 403 provide DC power for the first driving stage amplifier 100 , the second driving stage amplifier 200 and the output stage power amplifier 300 respectively. Meanwhile, the input matching transformer 400 forms the input matching network, the first inter-stage matching transformer 401, the capacitor 107 and the capacitor 108 form the first inter-stage matching network, and the second inter-stage matching transformer 402, the capacitor 207 and the capacitor 208 form the second inter-stage matching network Matching network, output matching transformer 403, capacitor 307 and capacitor 308 form a matching network between outputs.

Figure 2 is the result of the gain and input and output reflection coefficients of a broadband high linearity power amplifier. In the frequency range of 21-28GHz, the power amplifiers can achieve a maximum small signal gain of 22.5dB, and the in-band gain jitter is less than 1dB, which means that the present invention realizes a broadband and flat signal amplification function. At the same time, the power amplifier achieves good matching, and the input reflection coefficient is less than -10dB and the output reflection coefficient is less than -5dB at 24–28GHz.

Figure 3 is the result of the output 1dB compression point and the output 3dB compression point of the broadband high linearity power amplifier. In the frequency range of 24-27GHz, the output 1dB compression point of the power amplifier is greater than 15dBm, and the output 3dB compression point is greater than 15.5dBm, which means that the present invention realizes broadband high-power output.

Figure 4 is a result of the amplitude linearity of a broadband high linearity power amplifier. Before reaching the 1dB compression point, the gain uplift is less than 1dB, which means that the present invention achieves better amplitude linearity.

Figure 5 is a result of the phase linearity of a broadband high linearity power amplifier. Before reaching the 1dB compression point, the phase shift is less than 6°, which means that the present invention achieves better phase linearity.

Figure 6 is a result of third-order intermodulation (IMD3) of a broadband high linearity power amplifier. In a wide output power range, the third-order intermodulation amount below -30dBc is simultaneously achieved in the upper and lower sidebands.

A broadband high linearity power amplifier of the present invention has the following advantages:

First, the present invention proposes a differential capacitor neutralization amplifier structure with a second harmonic short circuit. On the one hand, the amplitude linearity and phase linearity of the power amplifier are improved, the third-order intermodulation is suppressed, and the The ability of the power amplifier to transmit high-power broadband high-order modulation signals, on the other hand, suppresses the influence of common mode interference signals, enhances the reliability of the power amplifier, and improves the overall working ability of the power amplifier at high frequencies;

Second, the present invention suppresses the influence of the second harmonic on the modulated signal by combining the differential capacitor neutralizing amplifier and the second harmonic short circuit, thereby improving the amplitude linearity and phase linearity of the power amplifier at high frequencies;

Third, the capacitors in the second harmonic short circuit are absorbed in the matching network, which eliminates the effect of the second harmonic short circuit on the fundamental wave without affecting the amplitude linearity and phase linearity of the power amplifier at high frequencies. influence of the signal.

Furthermore, it should be noted that, in this specification, "comprising", "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device including a series of elements includes not only those elements, but also other elements not expressly listed or inherent to such a process, method, article or apparatus. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in a process, method, article or apparatus that includes the element.

It should be understood that although this specification is described in terms of embodiments, not every embodiment only includes an independent technical solution, and this description in the specification is only for the sake of clarity, and those skilled in the art should take the specification as a whole, and each The technical solutions in the embodiments can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims (9)

1. The broadband high-linearity power amplifier is characterized by comprising an input matching network, a first-stage driving amplifier (100), a first-stage matching network, a second-stage driving amplifier (200), a second-stage matching network, an output-stage power amplifier (300) and an output matching network which are sequentially connected, wherein the first-stage driving amplifier (100), the second-stage driving amplifier (200) and the output-stage power amplifier (300) respectively comprise differential capacitance neutralizing amplifiers (110, 210 and 310) and second-harmonic short circuits (120, 220 and 320) which are arranged in bilateral symmetry.

2. A wideband high linearity power amplifier according to claim 1, characterized in that: the input matching network, the first inter-stage matching network, the second inter-stage matching network and the output matching network are respectively realized on the basis of an input matching transformer (400), a first inter-stage matching transformer (401), a second inter-stage matching transformer (402) and an output matching transformer (403); the transformers (400, 401, 402, 403) are all integrated transformers on chip, and are realized by overlapping inductive coils formed by different metal layers.

3. A wideband high linearity power amplifier according to claim 3, characterized in that: the input matching transformer (400), the first inter-stage matching transformer (401) and the second inter-stage matching transformer (402) are implemented in the form of a weakly coupled transformer, and the output matching transformer (403) is implemented in the form of a strongly coupled transformer, wherein: the first inter-stage matching transformer (401), the second inter-stage matching transformer (402) and the output matching transformer (403) respectively provide direct current power for the first drive stage amplifier (100), the second drive stage amplifier (200) and the output stage power amplifier (300).

4. A wideband high linearity power amplifier according to claim 1, characterized in that: the first-stage driver amplifier (100), the second-stage driver amplifier (200) and the output-stage power amplifier (300) have the same structure.

5. A wideband high linearity power amplifier according to claim 4, characterized in that: the differential capacitance neutralization amplifier (110) of the first-stage drive amplifier (100) is composed of a first transistor (101), a second transistor (102), a first capacitor (103) and a second capacitor (104), the device sizes of the first transistor (101) and the second transistor (102) are the same, and the first capacitor (103) and the second capacitor (104) are the same; the grid electrode of the first transistor is connected with a first capacitor (103) in series and then connected to the drain electrode of a second transistor (102), the grid electrode of the second transistor is connected with a second capacitor (104) in series and then connected to the drain electrode of the first transistor (101), and the grid electrodes and the drain electrodes of the first transistor (101) and the second transistor (102) are respectively connected to a differential signal path; the differential capacitance neutralization amplifier (210) of the second stage drive amplifier (200) comprises third to fourth transistors (201, 202) and fifth to sixth capacitors (203, 204); the differential capacitance neutralization amplifier (310) of the output stage power amplifier (300) comprises fifth to sixth transistors (301, 302) and ninth to tenth capacitors (303, 304).

6. A wideband high linearity power amplifier according to claim 4, characterized in that: the second harmonic short circuit (120) of the first-stage drive amplifier (100) is composed of a first inductor (105), a second inductor (106), a third capacitor (107) and a fourth capacitor (108), wherein the first inductor (105) is the same as the second inductor (106), and the third capacitor (107) is the same as the fourth capacitor (108); one end of a first inductor (105) is connected with the source electrode of the first transistor (101), the other end of the first inductor is connected with the source electrode of the second transistor (102) after being connected with a second inductor (106) in series, one end of a third capacitor (107) is connected with the drain electrode of the first transistor (101), the other end of the third capacitor is connected with the drain electrode of the second transistor (102) after being connected with a fourth capacitor (108) in series, and the joint of the third capacitor (107) and the fourth capacitor (108) is connected with the joint of the first inductor (105) and the second inductor (106); a second harmonic short circuit (220) of the second stage driver amplifier (200) comprises seventh to eighth capacitors (207, 208) and third to fourth inductors (205, 206); the second harmonic short circuit (320) of the output stage power amplifier (300) includes eleventh to twelfth capacitors (307, 308) and fifth to sixth inductors (305, 306).

7. A wideband high linearity power amplifier according to claim 4, characterized in that: the device size of the differential capacitance neutralization amplifier (110, 210, 310) in the first stage driver amplifier (100), the second stage driver amplifier (200) and the output stage power amplifier (300) is increased proportionally, wherein: the device size ratio of the first to second transistors (101, 102), the third to fourth transistors (201, 202), and the fifth to sixth transistors (301, 302) is 2: 3: 4; the capacitance value ratio of the first to second capacitors (103, 104), the fifth to sixth capacitors (203, 204) and the ninth to tenth capacitors (303, 304) is 2: 3: 4.

8. a wideband high linearity power amplifier according to claim 4, characterized in that: the device sizes of second harmonic short-circuit circuits (120, 220, 320) in the first-stage driver amplifier (100), the second-stage driver amplifier (200) and the output-stage power amplifier (300) are the same, and the inductance values of the first-sixth inductors (105, 106, 205, 206, 305, 306) are the same; the capacitance values of the third to fourth capacitors (107, 108), the seventh to eighth capacitors (207, 208) and the eleventh to twelfth capacitors (307, 308) are the same.

9. A wideband high linearity power amplifier according to claim 3, characterized in that: the input matching transformer (400) forms an input matching network, the first inter-stage matching transformer (401) and the third to fourth capacitors (107 and 108) form a first inter-stage matching network, the second inter-stage matching transformer (402) and the seventh to eighth capacitors (207 and 208) form a second inter-stage matching network, and the output matching transformer (403) and the eleventh to twelfth capacitors (307 and 308) form an output inter-stage matching network.

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