WO2018023215A1

WO2018023215A1 - Envelope modulator, envelope tracking power amplifier and communication device

Info

Publication number: WO2018023215A1
Application number: PCT/CN2016/092500
Authority: WO
Inventors: 庞志远; 朱胜; 俞雪明; 力争; 王明贵
Original assignee: 华为技术有限公司
Priority date: 2016-07-30
Filing date: 2016-07-30
Publication date: 2018-02-08
Also published as: CN109417394A; CN109417394B

Abstract

An envelope modulator (50), comprising an envelope amplifier (51), an operating voltage source and a floating voltage circuit (53), wherein the envelope amplifier (51) comprises an operating voltage input end (511), an envelope signal input end (513), a reference voltage input end (515) and an envelope signal output end (517); an anode of the operating voltage source is electrically connected to the operating voltage input end (511), and a cathode thereof is electrically connected to the reference voltage input end (515); the floating voltage circuit (53) is connected between the reference voltage input end (515) and the ground and is used for providing a reference voltage for the envelope amplifier (51); and the envelope signal input end (513) is used for inputting a first envelope signal, the envelope amplifier (51) is used for generating a second envelope signal according to the first envelope signal and the reference voltage, and the envelope signal output end (517) is used for outputting the second envelope signal. The envelope modulator (50) has better envelope conversion efficiency and operating bandwidth.

Description

Envelope modulator, envelope tracking power amplifier and communication device

Technical field

The present invention relates to the field of communications technologies, and in particular, to an envelope modulator and an envelope tracking power amplifier and a communication device using the envelope modulator.

Background technique

The RF power amplifier (hereinafter referred to as the power amplifier) is an indispensable part of the wireless base station. The efficiency of the power amplifier determines the power consumption, size and thermal design of the base station. At present, in order to improve the transmission rate of a base station, wireless communication uses a plurality of different modulation signals, such as Orthogonal Frequency Division Multiplexing (OFMA) and Code-Division Multiple Access (CDMA). Time division multiple access (TDMA), etc., according to the relevant protocol, the modulation signals of these standards have different Peak-to-Average Power Ratio (PAPR), such as the peak-to-average ratio of OFDM. It is 10 to 12 dB. The peak-to-average signal has higher linearity requirements for the power amplifier in the base station, such as the Adjacent Channel Leakage Power Ratio (ACLR). In order to meet these indicators, one method is to use power back-off, that is, to make the power amplifier work in the class A or class AB state, but according to the characteristics of the power amplifier tube, this will cause a large drop in the efficiency of the power amplifier, and the base station is also under the same output power. Energy consumption has increased significantly.

For the application of peak-to-average ratio signals, another method is to combine high-efficiency nonlinear power amplifiers with linear digital technologies such as Digital Pre-Distortion (DPD). This can get better power amplifier efficiency, and the linearity of the power amplifier can also meet the requirements of relevant protocols. There are many high-efficiency nonlinear power amplifier technologies. Currently, there are Doherty technologies and Envelope Tracking (ET) technologies that are being researched. ET technology uses signal envelopes for dynamic control. The drain or collector voltage of the RF power amplifier keeps the power close to saturation when it is placed at different output powers, thus achieving high efficiency. The block diagram of the envelope tracking power amplifier in the prior art is shown in FIG. 1. The envelope tracking power amplifier is composed of an envelope amplifier (Envelope Amplifier) and an RF power amplifier (RF Power Amplifier), and the entire envelope tracks the efficiency of the power amplifier. It is determined by the efficiency product of the two, namely: η _tot = η _VDD × η _RF , where η _tot is the efficiency of the entire envelope tracking power amplifier, η _VDD is the efficiency of the envelope amplifier, and η _RF is the efficiency of the RF amplifier.

For the characteristics of the modulated signal, for example, an OFDM signal with a bandwidth of 20 MHz, 85% of the energy of the envelope signal is concentrated in the range of DC to several hundred kHz, and 99% of the energy is concentrated within 20 MHz. One of the prior art is to adopt linearity. A Hybrid structure consisting of an amplifier and a Buck switch circuit. The high frequency part is amplified by a linear amplifier (such as a Class AB amplifier), and the lower frequency signal is amplified by a switching amplifier, thereby avoiding the use of a higher switching frequency.

As shown in FIG. 2, the envelope amplifier in the envelope tracking power amplifier of the prior art is composed of a linear amplifier (Amplifier) and a switching amplifier (Buck Switcher), and the switching amplifier is more efficient because it operates in a switching state. The linear amplifier consists of an amplifier with low output resistance, high gain-bandwidth product, and large slew rate, which is characterized by wide bandwidth and good linearity. This segmented modulation structure allows the envelope amplifier to have higher bandwidth and linearity while meeting high efficiency. The key to this technique of amplifying the envelope signals separately is the linear amplifier in Figure 2. The higher the peak-to-average ratio of the RF signal, the larger the power output of the amplifier and the larger the envelope amplitude. Therefore, the output amplitude of the linear amplifier is also required to be higher. Since the linear amplifier gain bandwidth product (GBW) is constant, the larger the output amplitude is, the higher the gain is, and the lower the operating bandwidth is. In addition, the higher the operating voltage of the switching amplifier in FIG. 2, the greater the loss, resulting in a lower conversion efficiency of the envelope amplifier. Therefore, the envelope amplifier using the prior art one has a lower operating bandwidth and conversion efficiency.

As shown in FIG. 3, the envelope amplifier of the prior art 2 uses a parallel structure in which the output of the multi-phase switching circuit is combined through an inductor, and the switching circuit adopts a Pulse Width Modulation (PWM) technique. The input signal controls the Multiphase Modulator to generate multiple PWM signals. Each PWM signal controls a pair of Buck switch circuits. The output of the switch circuit is a pulse signal with a fixed voltage amplitude and a width varying with the input signal size. The output of the multiphase switching circuit is combined by the inductor and filtered to recover the signal envelope. However, at the peak-to-average ratio and high-power output, the operating voltage of the switching circuit is increased due to the increase of the envelope amplitude, resulting in higher tracking error voltage, lower tracking accuracy, higher noise on the envelope, and higher noise of the power amplifier. bottom. At the same time, the operating voltage is increased, and the loss of the switching circuit is also increased, resulting in a decrease in the efficiency of the envelope amplifier.

As shown in FIG. 4, the envelope amplifier of the prior art 3 quantizes the envelope into a plurality of discrete voltages, A plurality of discrete voltages are output to the load by the envelope control time division. In order to achieve a certain tracking accuracy, it is necessary to have a plurality of different voltages. For example, in order to achieve 1/2N tracking accuracy, 2N voltages and 2N comparison control links are required, resulting in high circuit overhead and high cost.

In summary, the envelope amplifier in the envelope tracking power amplifier of the prior art has problems of high loss, narrow working bandwidth, and low conversion efficiency. Therefore, in order to reduce the power consumption of communication devices such as base stations and improve signal transmission bandwidth and transmission efficiency, it is necessary to improve the envelope amplifier of the envelope tracking power amplifier in the prior art.

Summary of the invention

In view of the problems in the prior art, embodiments of the present invention provide an envelope modulator and an envelope tracking power amplifier and a communication device using the envelope modulator to reduce an operating voltage and work of an envelope tracking power amplifier. The envelope is used to track the signal transmission bandwidth and transmission efficiency of the power amplifier and the communication device.

A first aspect of the embodiments of the present invention provides an envelope modulator, including an envelope amplifier, an operating voltage source, and a floating voltage circuit, where the envelope amplifier includes an operating voltage input terminal, an envelope signal input terminal, and a reference voltage input terminal. An envelope signal output end, wherein a positive pole of the working voltage source is electrically connected to the working voltage input end, a negative pole of the working voltage source is electrically connected to the reference voltage input end, and the floating voltage circuit is connected to the reference Between the voltage input terminal and ground, for providing a reference voltage for the envelope amplifier, the envelope signal input terminal for inputting a first envelope signal, and the envelope amplifier for using the first envelope The signal and the reference voltage generate a second envelope signal, the envelope signal output for outputting the second envelope signal.

The envelope modulator is configured to provide the reference voltage between the reference voltage input terminal of the envelope amplifier and ground to provide a reference voltage to the envelope amplifier through the floating voltage circuit, thereby effectively reducing the voltage The operating voltage of the envelope amplifier increases the operating bandwidth of the envelope amplifier. Compared with the prior art switched envelope amplifier, the switching loss can be effectively reduced, thereby improving the efficiency and tracking accuracy of the envelope amplifier.

In conjunction with the first aspect, in a first possible implementation manner of the first aspect, the floating voltage circuit includes a first voltage source, and a positive pole of the first voltage source is electrically connected to the reference voltage input end, A negative pole of the first voltage source is grounded, and the reference voltage is equal to a voltage of the first voltage source.

By using the first voltage source as the floating voltage circuit, such that the reference voltage of the envelope amplifier is always maintained at the same voltage as the first voltage source, when the first envelope signal passes through the packet The actual output voltage of the envelope amplifier is zero when the ideal output envelope signal amplified by the amplifier is less than or equal to the reference voltage, and the envelope is when the ideal output envelope signal is greater than the reference voltage The actual output voltage of the amplifier is the voltage of the second envelope signal minus the reference voltage. Therefore, due to the presence of the reference voltage, the maximum actual output voltage amplitude of the envelope amplifier is reduced, so that the operating bandwidth of the envelope amplifier can be effectively increased.

With reference to the first possible implementation manner of the first aspect, in a second possible implementation manner of the first aspect, the floating voltage circuit further includes a second voltage source to an nth voltage source and the first switch tube to the nth a switching tube, the anode of the first voltage source is electrically connected to the reference voltage input end through the first switching tube, and the anode of the kth voltage source is electrically connected to the reference voltage input end through a kth switching tube The negative electrode of the kth voltage source is connected to the positive electrode of the k-1th voltage source, wherein n is a positive integer greater than or equal to 2, and k is a positive integer greater than or equal to 2 and less than or equal to n.

The floating voltage circuit is connected to the reference voltage input end of the envelope amplifier through a switch tube by setting n voltage sources connected in series with each other, so that the switch can be turned on by switching different switch tubes. The reference amplifiers are provided with different sized reference voltages to facilitate adjustment of the operating voltage and bandwidth of the envelope amplifier by different reference voltages.

In conjunction with the second possible implementation of the first aspect, in a third possible implementation manner of the first aspect, the first switch is turned on, the remaining switches are turned off, and the reference voltage is equal to the first voltage a voltage of the source; the kth switch is turned on, and the remaining switches are turned off, and the reference voltage is equal to a sum of voltages of the k voltage sources of the first voltage source to the kth voltage source.

With reference to the second possible implementation manner of the first aspect or the third possible implementation manner of the first aspect, in a fourth possible implementation manner of the first aspect, the nth voltage source is the working voltage source, The envelope modulator further includes a first diode, a second diode, a first capacitor and a second capacitor, a positive pole of the nth voltage source and a positive pole of the first diode and the first a cathode of the second diode is connected, a cathode of the nth voltage source is connected to a positive pole of the n-1th voltage source, and a cathode of the first diode is connected to the working voltage input end, the second a cathode of the pole tube is connected to the reference voltage input end through an nth switch, the first capacitor is connected between the working voltage input end and the reference voltage input end, and the second capacitor is connected to the Positive electrode of the second diode and positive of the n-1th voltage source Between the poles.

By sharing the working voltage source as the nth voltage source and providing isolation by the first diode and the second diode, it is ensured that the operating power supply is provided for the envelope amplifier At the same time of the operating voltage, the nth voltage source can also be shared, so that the complexity and power consumption of the envelope modulator can be reduced to some extent, and the production cost can be reduced.

With reference to the first possible implementation manner of the first aspect, in a fifth possible implementation manner of the first aspect, the floating voltage circuit further includes a second voltage source to an nth voltage source and the first switch tube to the nth a switching tube, the anode of the first voltage source is electrically connected to the reference voltage input end through the first switching tube, and the anode of the kth voltage source is electrically connected to the reference voltage input end through a kth switching tube A negative electrode of the kth voltage source is connected to a positive electrode of the first voltage source, wherein n is a positive integer greater than or equal to 2, and k is a positive integer greater than or equal to 2 and less than or equal to n.

The floating voltage circuit is connected to the reference voltage input end of the envelope amplifier through a switch tube by setting n voltage sources connected in parallel with each other, so that the switch can be turned on by switching different switch tubes. The reference amplifiers are provided with different sized reference voltages to facilitate adjustment of the operating voltage and bandwidth of the envelope amplifier by different reference voltages.

With reference to the fifth possible implementation manner of the first aspect, in a sixth possible implementation manner of the first aspect, the first switch is turned on, the remaining switches are turned off, and the reference voltage is equal to the first voltage a voltage of the source; the kth switch is turned on, and the remaining switches are turned off, and the reference voltage is equal to a sum of a voltage of the first voltage source and a voltage of the kth voltage source.

In conjunction with the fifth possible implementation of the first aspect or the sixth possible implementation of the first aspect, in a seventh possible implementation of the first aspect, the envelope modulator further includes a first diode a second diode, a first capacitor, and a second capacitor, wherein a positive electrode of the nth voltage source is connected to a positive electrode of the first diode and an anode of the second diode, the nth voltage a cathode of the source is coupled to the anode of the first voltage source, a cathode of the first diode is coupled to the input voltage input terminal, and a cathode of the second diode is coupled through the nth switch transistor and the reference The voltage input is connected, the first capacitor is connected between the working voltage input end and the reference voltage input end, and the second capacitor is connected to the negative pole of the second diode and the first voltage Between the positive poles of the source.

With reference to the second possible implementation of the first aspect, to any one of the possible implementations of the seventh possible implementation of the first aspect, in the eighth possible implementation of the first aspect, the floating voltage circuit a first driver to an nth driver, each of the switch transistors including a gate, a source and a drain, a gate of the first switch being connected to the first driver, the first switch a source is connected to the anode of the first voltage source, a drain of the first switch tube is connected to the reference voltage input end, and a gate of the kth switch tube is connected to a kth driver, the kth A source of the switching transistor is connected to the reference voltage input terminal, and a drain of the kth switching transistor is connected to an anode of the kth voltage source.

By setting a driver for each of the switch tubes, and then controlling the turn-on or turn-off of one of the switch tubes by each of the drivers, the output voltage of the floating voltage circuit can be conveniently adjusted, that is, the envelope amplifier is adjusted. The reference voltage facilitates adjustment of the operating voltage and bandwidth of the envelope amplifier.

In conjunction with the eighth possible implementation of the first aspect, in a ninth possible implementation manner of the first aspect, the reference voltage of the first driver is equal to a voltage of the first voltage source, where the kth driver The reference voltage is equal to the reference voltage at the input of the reference voltage and varies as the reference voltage changes.

By setting the reference voltage of the kth driver to be the same as the reference voltage and varying with the change of the reference voltage, thereby being adjustable from a lower reference voltage to a higher reference voltage, The normal conduction of the switch tube corresponding to the higher reference voltage is ensured, that is, the stable operation of the floating voltage circuit is ensured.

With reference to the second possible implementation of the first aspect, to any one of the possible implementations of the seventh possible implementation of the first aspect, in the tenth possible implementation manner of the first aspect, the floating voltage circuit The driver further includes n output ports, each of the output ports respectively for providing one control signal, and each of the control signals is used for controlling the on or off of one of the switch tubes.

The n-channel control signal is provided by a driver, and the complexity of the floating voltage circuit can be effectively reduced relative to the scheme of the plurality of drivers, and the power consumption of the envelope modulator can be reduced.

A second aspect of the present invention provides an envelope tracking power amplifier, including a radio frequency power amplifier, and a first aspect of the first embodiment of the present invention and a first possible implementation of the first aspect to a tenth possible implementation manner of the first aspect. The envelope modulator of any one of the implementations, the envelope modulator being coupled to the radio frequency power amplifier for providing an envelope signal for the radio frequency power amplifier.

A third aspect of the embodiments of the present invention provides a communication device comprising the envelope tracking power amplifier according to the second aspect of the present invention.

The envelope modulator is configured to provide the reference voltage between the reference voltage input terminal of the envelope amplifier and ground to provide a reference voltage to the envelope amplifier through the floating voltage circuit, thereby effectively reducing the voltage The operating voltage of the envelope amplifier, in turn, reduces the power consumption of the envelope tracking power amplifier and the communication device. At the same time, by providing the reference voltage, the operating bandwidth of the envelope amplifier can be improved, and the efficiency and tracking accuracy of the envelope amplifier can be improved, thereby improving the performance of the envelope tracking power amplifier and the communication device.

DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly described below.

1 is a schematic block diagram of an envelope tracking power amplifier in the prior art;

2 is a schematic structural diagram of an envelope amplifier of an envelope tracking power amplifier of the prior art;

3 is a schematic structural diagram of an envelope amplifier of an envelope tracking power amplifier of the prior art 2;

4 is a schematic structural diagram of an envelope amplifier of an envelope tracking power amplifier of the prior art 3;

FIG. 5 is a schematic diagram of a first structure of an envelope modulator according to an embodiment of the present invention; FIG.

6a to 6b are schematic diagrams showing waveform comparison of an output envelope signal of the envelope modulator shown in FIG. 5;

7a to 7c are waveform diagrams showing output signals of a floating voltage circuit and an envelope amplifier of the envelope modulator shown in FIG. 5;

FIG. 8 is a second schematic structural diagram of an envelope modulator according to an embodiment of the present invention; FIG.

FIG. 9 is a third schematic structural diagram of an envelope modulator according to an embodiment of the present invention; FIG.

10a to 10c are schematic diagrams showing waveform comparisons of output envelope signals of the envelope modulator shown in FIG. 9;

11 is a fourth schematic structural diagram of an envelope modulator according to an embodiment of the present invention;

FIG. 12 is a schematic diagram showing a fifth structure of an envelope modulator according to an embodiment of the present invention; FIG.

FIG. 13 is a schematic structural diagram of an envelope tracking power amplifier according to an embodiment of the present invention.

detailed description

The technical solutions in the embodiments of the present invention will be described below with reference to the accompanying drawings in the embodiments of the present invention.

Referring to FIG. 5, in an embodiment of the present invention, an envelope modulator 50 is provided, including an envelope amplifier 51, an operating voltage source VDD, and a floating voltage circuit 53. The envelope amplifier 51 includes an operating voltage input terminal 511, an envelope signal input terminal 513, a reference voltage input terminal 515, and an envelope signal output terminal 517. The anode of the working voltage source VDD is electrically connected to the working voltage input terminal 511, and the cathode of the working voltage source VDD is electrically connected to the reference voltage input terminal 515. The floating voltage circuit 53 is connected between the reference voltage input terminal 515 and the ground for providing a reference voltage Vfloat for the envelope amplifier 51, and the envelope signal input terminal 513 is configured to input a first envelope signal. The envelope amplifier 51 is configured to generate a second envelope signal according to the first envelope signal and the reference voltage Vfloat, and the envelope signal output end 517 is configured to output the second envelope signal.

As shown in FIG. 5, in one embodiment, the floating voltage circuit 53 includes a first voltage source Vg1, a second voltage source Vg2, a first switching transistor M1, a second switching transistor M2, and a driver Driver. The anode of the first voltage source Vg1 is electrically connected to the reference voltage input terminal 515 through the first switch tube M1, and the cathode of the first voltage source Vg1 is grounded. The anode of the second voltage source Vg2 is electrically connected to the reference voltage input terminal 515 through the second switch transistor M2, and the cathode of the second voltage source Vg2 is connected to the anode of the first voltage source Vg1.

In this embodiment, the first switch tube M1 and the second switch tube M2 each include a gate g, a source s, and a drain d. The driver includes a control terminal Ctrl, a first output terminal P1, and a second output terminal P2. The gate g of the first switch M1 is connected to the first output terminal P1, and the source s of the first switch M1 is connected to the anode of the first voltage source Vg1, the first switch tube The drain d of M1 is coupled to the reference voltage input 515. a gate g of the second switch M2 is connected to the second output terminal P2, a source s of the second switch transistor M2 is connected to the reference voltage input terminal 515, and the second switch transistor M2 is The drain d is connected to the anode of the second voltage source Vg2. Wherein, the control terminal Ctrl of the driver is used for connecting with a controller (not shown) to be in the controller Controlling, outputting a first control signal through the first output terminal P1 to control the first switch tube M1 to be turned on or off, and outputting a second control signal through the second output terminal P2 to control the second The switch tube M2 is turned on or off. In this embodiment, the first control signal and the second control signal are both square wave signals, and the first control signal is complementary to the second control signal, so that the first switch tube M1 When the second switch tube M2 is turned on, the first switch tube M1 is turned off. It can be understood that the first control signal and the second control signal may also be provided by two drivers respectively. For example, the first driver provides a first control signal and the second driver provides a second control signal.

Please refer to FIG. 6 and FIG. 7 together, wherein FIG. 6a is a waveform diagram of an ideal output envelope signal, and FIG. 6b is an actual output envelope signal of the envelope modulator shown in FIG. 5 (ie, the second envelope signal Corresponding to the waveform diagram of Vo) in FIG. 5; FIG. 7a is a schematic diagram of the output voltage waveform of the first voltage source Vg1 (corresponding to Vg1 in FIG. 5), and FIG. 7b is the output of the second voltage source Vg2 A schematic diagram of the voltage waveform (corresponding to Vg2_o in FIG. 5), and FIG. 7c is a waveform diagram of the output voltage of the envelope amplifier 51 (corresponding to VDD_o in FIG. 5).

When the voltage of the ideal output envelope signal is less than or equal to Vg1 (ie, from 0 to t1), the driver outputs a first control signal of a high level through the first output terminal P1 to control the first switch. The tube M1 is turned on, and the second output terminal P2 outputs a second control signal of a low level, and the second switch tube M2 is controlled to be turned off, that is, the reference voltage Vfloat=Vg1; at this time, the envelope The output voltage of the amplifier 51 is zero, that is, VDD_o=0.

When the voltage of the ideal output envelope signal is greater than Vg1 and less than or equal to Vg1+Vg2 (ie, time t1 to t2), the driver outputs a first control signal of a high level through the first output terminal P1, and controls The first switch tube M1 is turned on, and outputs a second control signal of a low level through the second output terminal P2 to control the second switch tube M2 to be turned off, that is, the reference voltage Vfloat=Vg1; The output voltage VDD_o=Vo-Vfloat of the envelope amplifier 51.

When the voltage of the ideal output envelope signal is greater than Vg1+Vg2 and less than or equal to the highest envelope voltage Vmax, the driver outputs a first control signal of a low level through the first output terminal P1 to control the first a switching transistor M1 is turned off, and a second control signal of a high level is output through the second output terminal P2, and the second switching transistor M2 is controlled to be turned on, that is, a reference voltage Vfloat=Vg1+Vg2_o=Vg1+Vg2; At the time, the output voltage of the envelope amplifier 51 is VDD_o=Vo-Vfloat=Vo- Vg1-Vg2.

In this embodiment, the first switch tube M1 and the second switch tube M2 are both NMOS tubes, that is, a certain on-voltage Vgs needs to be applied between the gate g and the source s to drive the device. The switch tube is turned on. Assuming that the turn-on voltage of the first switch M1 and the second switch M2 is Vgs, the low level of the first control signal may be used (ie, the driver is used to generate the first control signal) Set the reference voltage to Vg1, set the high level of the first control signal to Vg1+Vgs, and set the low level of the second control signal (ie, the driver is used to generate the second control) The reference voltage of the signal is set to be the same as the voltage Vfloat of the reference voltage input terminal 515 (corresponding to the CM terminal in FIG. 5), and the high level of the second control signal is set to Vfloat+Vgs. It can be understood that since the switch state is changed from M1 on, M2 off to M1 off, and M2 is not on, the voltage at the CM terminal is still Vfloat=Vg1. At this time, to turn on M2, the second control only needs to be performed. The high level of the signal can be set to Vg1+Vgs. When M2 is fully turned on, the voltage at the CM terminal is pulled up to Vfloat=Vg1+Vg2. At this time, to maintain the conduction of M2, the high level of the second control signal needs to be set to Vg1+Vg2+Vgs. . Therefore, in order to ensure the normal conduction of the M2, a low level of the second control signal may be set by setting a bootstrap capacitor (not shown), so that the low level of the second control signal is always maintained. Vfloat changes synchronously.

In the present embodiment, taking Vg2 = VDD = (Vmax - Vg1) / 2, the maximum value of the output voltage VDD_o of the envelope amplifier 51 = Vmax - Vg1 - Vg2 = (Vmax - Vg1)/2. It can be seen that by setting the floating voltage circuit 53 between the reference voltage input terminal 515 and the ground, the output voltage amplitude of the envelope amplifier 51 can be reduced by more than half of the amplitude of the ideal output envelope signal. And the gain of the envelope amplifier 51 can be reduced by more than 3 dB, so that the bandwidth of the envelope modulator 50 can be more than doubled. At the same time, since the output voltage VDD_o of the envelope amplifier 51 is reduced, the error voltage it brings is also reduced, so that the actual output envelope signal (ie, the second envelope signal Vo) has lower spectral noise. In addition, the envelope modulator 50 can also reduce switching losses, resulting in higher efficiency.

Referring to FIG. 8, in an embodiment, an envelope modulator 50' is provided, which differs from the envelope modulator 50 shown in FIG. 5 in that the operating voltage source VDD is used as a floating voltage circuit 53. The second voltage source Vg2 is provided with isolation by providing the first diode D1 and the second diode D2, and is stored by providing the first capacitor C1 and the second capacitor C2. Specifically, the second voltage a positive electrode of the source Vg2 (ie, the operating voltage source VDD) is connected to a positive electrode of the first diode D1 and a positive electrode of the second diode D2, and a negative electrode of the second voltage source Vg2 and the first A positive terminal of a voltage source Vg1 is connected, a negative electrode of the first diode D1 is connected to the operating voltage input terminal 513, and a negative electrode of the second diode D2 is passed through the second switching transistor M2 and the reference The voltage input terminal 515 is connected, the first capacitor C1 is connected between the working voltage input terminal 513 and the reference voltage input terminal 515, and the second capacitor C2 is connected to the cathode of the second diode D2. Between the positive electrode of the first voltage source Vg1. It will be appreciated that the envelope modulator 50' is essentially identical to the envelope modulator 50 of Figure 5, but achieves a cost effective effect by sharing the operating voltage source VDD. For the function of the envelope modulator 50', reference may be made to the related description in the embodiment shown in FIG. 5, and details are not described herein again.

Referring to FIG. 9, in an embodiment, an envelope modulator 150 is provided, including an envelope amplifier 151, an operating voltage source VDD, and a floating voltage circuit 153. The envelope amplifier 151 includes an operating voltage input terminal 1511, an envelope signal input terminal 1513, a reference voltage input terminal 1515, and an envelope signal output terminal 1517. The envelope modulator 150 differs from the envelope modulator 50 shown in FIG. 5 in that the floating voltage circuit 153 includes a first voltage source Vg1, a positive pole of the first voltage source Vg1 and the reference voltage input. The terminal 1515 is electrically connected, the negative pole of the first voltage source Vg1 is grounded, and the reference voltage Vfloat is equal to the voltage of the first voltage source Vg1.

Please refer to FIG. 10, wherein FIG. 10a is a waveform diagram of an ideal output envelope signal, and FIG. 10b is an output envelope signal of the envelope modulator 150 shown in FIG. 9 (ie, the second envelope signal corresponds to FIG. FIG. 10c is a waveform diagram of the output voltage of the envelope amplifier 151 of the envelope modulator 150 shown in FIG. 9 (corresponding to VDD_o in FIG. 9).

When the voltage of the ideal output envelope signal is less than or equal to the reference voltage Vfloat (ie, 0 to t1), the output voltage VDD_o of the envelope amplifier 151 is zero, that is, VDD_o=0, the envelope modulation The voltage of the output envelope signal of the device 150 is constant at Vfloat. When the voltage of the ideal output envelope signal is greater than the reference voltage Vfloat (ie, time t1 to t2), the output voltage VDD_o=Vo-Vfloat of the envelope amplifier 151, the output of the envelope modulator 150 The voltage of the envelope signal is the actual envelope voltage (ie, the voltage of the ideal output envelope signal). It can be seen that by setting the floating voltage circuit 153 (ie, the first voltage source Vg1) between the reference voltage input terminal 1515 and the ground, the maximum output voltage amplitude of the envelope amplifier 151 can be made initial. Value Vmax Reduce to Vmax-Vfloat. If Vfloat=Vg1=Vmax/2 is set, the maximum output voltage amplitude of the envelope amplifier 151 can be reduced by half. When the voltage of the ideal output envelope signal is the same, by setting the floating voltage circuit 153, The gain of the envelope amplifier 151 can be reduced by 3 dB, thereby doubling the bandwidth of the envelope amplifier 151. Since when the voltage of the ideal output envelope signal is less than or equal to the reference voltage Vfloat, the voltage of the output envelope signal of the envelope modulator 150 is constant to Vfloat, which may result in the application of the envelope modulator 150. The envelope tracking power amplifier is reduced in efficiency. Therefore, the selection of the reference voltage Vfloat is related to the application of the envelope of the envelope modulator to track the efficiency and bandwidth equalization of the power amplifier. For example, when the Vfloat is low, the efficiency of the envelope tracking power amplifier is high, but the envelope amplifier needs to output a larger voltage amplitude, and the envelope tracking power amplifier has a lower efficiency bandwidth; conversely, if the Vfloat is higher, the packet is made. The efficiency of the tracking power amplifier is low, but the bandwidth of the envelope tracking power amplifier is improved.

Referring to FIG. 11, in an embodiment, an envelope modulator 350 is provided, including an envelope amplifier 351, an operating voltage source VDD, and a floating voltage circuit 353. The envelope amplifier 351 includes an operating voltage input terminal 3511, an envelope signal input terminal 3513, a reference voltage input terminal 3515, and an envelope signal output terminal 3517. The difference between the envelope modulator 350 and the envelope modulator 150 shown in FIG. 9 is that the floating voltage circuit 353 further includes a second voltage source Vg2 (not shown) to an nth voltage source Vgn and a first switch. The tube M1 to the nth switch tube Mn, the anode of the first voltage source Vg1 is electrically connected to the reference voltage input terminal 3515 through the first switch tube M1, and the anode of the kth voltage source Vgk passes through the kth switch tube Mk Connected to the reference voltage input terminal 3515, the negative electrode of the kth voltage source Vgk is connected to the positive electrode of the k-1th voltage source Vgk-1 (not shown), where n is a positive integer greater than or equal to 2. , k is a positive integer greater than or equal to 2 and less than or equal to n. It can be understood that when n=2, k=2, the structure of the envelope modulator 350 is the same as that of the envelope modulator 50 shown in FIG.

The floating voltage circuit 353 further includes a first driver Driver 1 to an nth driver Driver n. Each of the first to nth switching tubes M1 to Mn includes a gate g, a source s, and a drain d. The gate g of the first switch tube M1 is connected to the first driver Driver 1, and the source s of the first switch tube M1 is connected to the anode of the first voltage source Vg1, the first switch tube The drain d of M1 is coupled to the reference voltage input 3515. The gate g of the kth switch Mk is connected to the kth driver Driver k, the source s of the kth switch Mk is connected to the reference voltage input terminal 3515, and the drain of the kth switch transistor Mk d is connected to the positive electrode of the kth voltage source Vgk.

It can be understood that, in this embodiment, each of the drivers is configured to provide a control signal for one of the switch tubes, thereby controlling the turn-on or turn-off of each of the switch tubes. In an optional implementation manner, a driver signal having n output ports can also be respectively provided with n control signals, and each control signal correspondingly controls whether one of the switch tubes is turned on or off, thereby effectively reducing circuit work. Consumption and complexity. For example, a n-way control signal can be generated by a signal generator having n output ports, each of which is respectively connected to a gate g of one of the switch tubes, and then through each of the control signals Controls the turn-on or turn-off of a switch. When n is equal to 2, two paths of control signals are respectively provided by one driver. For details, refer to the related description in the envelope modulator 50 shown in FIG.

In this embodiment, the first voltage source Vg1 to the nth voltage source Vgn are connected in series with each other, and each of the voltage sources is controlled by one of the switching tubes, thereby realizing flexibility of the reference voltage Vfloat. Adjustment. Specifically, when the first switch M1 is turned on, the reference voltage Vfloat=Vg1, when the kth switch Mk is turned on, the reference voltage Vfloat=Vg1+Vg2+...+Vgk. It can be understood that, at the same time, only one of the first switch tube M1, the kth switch tube Mk to the nth switch tube Mn is in an on state, and the other switch tubes are in an off state.

In this embodiment, the first switch tube M1 to the nth switch tube Mn are all NMOS transistors, that is, each of the switch tubes needs to apply a certain turn-on voltage Vgs between the gate g and the source s. Can be turned on. Therefore, a reference voltage can be set for each of the drivers as a low level of the driver, and the reference voltage is applied to the turn-on voltage Vgs as a high level of the driver, thereby ensuring high output when the driver is output. At the level, the voltage difference between the gate g and the source s of the corresponding switch tube is greater than or equal to the turn-on voltage, thereby controlling the corresponding switch tube to be turned on. According to the structural characteristics of the floating voltage circuit 353, in the present embodiment, the reference voltage of the first driver Driver 1 is equal to the voltage of the first voltage source Vg1, and the reference voltage of the kth driver Driver k is equal to The reference voltage Vfloat of the reference voltage input terminal 3515 is varied and varies with the change of the reference voltage Vfloat. For the selection of the reference voltage, reference may also be made to the related description in the embodiment shown in FIG. 5 to FIG. 7 , and details are not described herein again.

Referring to FIG. 12, in an embodiment, an envelope modulator 550 is provided, including an envelope amplifier 551, an operating voltage source VDD, and a floating voltage circuit 553. The envelope amplifier 551 includes an operating voltage input terminal 5511, an envelope signal input terminal 5513, a reference voltage input terminal 5515, and an envelope signal. Output 5517. The difference between the envelope modulator 550 and the envelope modulator 350 shown in FIG. 11 is that the anode of the first voltage source Vg1 is electrically connected to the reference voltage input terminal 5515 through the first switch tube M1. The positive electrode of the kth voltage source Vgk is electrically connected to the reference voltage input terminal 5515 through the kth switch transistor Mk, and the negative electrode of the kth voltage source Vgk is connected to the positive electrode of the first voltage source Vg1. Where n is a positive integer greater than or equal to 2, and k is a positive integer greater than or equal to 2 and less than or equal to n. Similarly, the floating voltage circuit 553 further includes first to nth drivers Driver 1 to N, each of which is used to control whether one of the switches is turned on or off. In this embodiment, the connection manner between each of the switch tubes and the driver, the voltage source, and the reference voltage input terminal 5515 is the same as that in the envelope modulator 350 shown in FIG. Correspondingly, the reference voltage of each of the drivers is also set in the same manner as in the envelope modulator 350 shown in FIG. 11, and details are not described herein again.

In this embodiment, the first voltage source Vg1 to the nth voltage source Vgn are connected in parallel with each other, and each of the voltage sources is controlled by one of the switching tubes, thereby realizing flexibility of the reference voltage Vfloat. Adjustment. When the first switch M1 is turned on, the reference voltage Vfloat is equal to the voltage of the first voltage source Vg1; when the kth switch Mk is turned on, the reference voltage Vfloat is equal to the first The sum of the voltage of the voltage source Vg1 and the voltage of the kth voltage source Vgk. It can be understood that the flexible adjustment of the reference voltage Vfloat can be realized by setting the second voltage source Vg2 (not shown) to the nth voltage source Vgn to different values respectively. For example, by setting the second voltage source Vg2 to the nth voltage source Vgn to sequentially increase the voltage, the second switch tube M2 (not shown) may be sequentially turned on to the nth switch tube Mn. The reference voltage Vfloat is sequentially incremented.

It can be understood that, in the specific engineering application, in order to save cost, the working voltage source VDD in the embodiment shown in FIG. 11 (or FIG. 12) can be shared as the nth in the floating voltage circuit 353 (or 553). The voltage source, that is, the nth voltage source is the operating voltage source VDD. To achieve good isolation, in an embodiment of the shared operating voltage source VDD, the envelope modulator 350 (or 550) further includes a first diode D1, a second diode D2, and a first capacitor C1. And a second capacitor C2, wherein a positive electrode of the nth voltage source Vgn is connected to a positive electrode of the first diode D1 and a positive electrode of the second diode D2, and a negative electrode of the nth voltage source Vgn and a first A positive electrode of the n-1 voltage source (or a positive electrode of the first voltage source Vg1) is connected, and a negative electrode of the first diode D1 and the operating voltage are connected The input terminal 3513 (or 5513) is connected, and the cathode of the second diode D2 is connected to the reference voltage input terminal 3515 (or 5515) through the nth switch tube Mn, and the first capacitor C1 is connected to the work. The voltage input terminal 3513 (or 5513) is connected to the reference voltage input terminal 3515 (or 5515), and the second capacitor C2 is connected to the negative electrode of the second diode D2 and the n-1th voltage source. Between the positive pole (the positive pole of the first voltage source Vg1). Wherein, the corresponding connection manner in FIG. 12 is indicated in parentheses, and when n=2, k=2, the first diode D1, the second diode D2, the first capacitor C1 and the second capacitor C2 are The connection relationship can also refer to the related description in the embodiment shown in FIG.

Referring to FIG. 13, in an embodiment of the present invention, an envelope tracking power amplifier 100 is further provided, including a radio frequency power amplifier 110 and an envelope modulator 130, and the envelope modulator 130 and the radio frequency power amplifier 110. A connection is provided for providing an envelope signal to the RF power amplifier 110. Specifically, the radio frequency power amplifier 110 includes a radio frequency signal input end 111, an envelope signal input end 113, a reference potential end 115, and a radio frequency signal output end 117. The envelope modulator 130 includes an envelope signal output 131. The radio frequency signal input end 111 is configured to input a first radio frequency signal, and the envelope signal input end 113 is connected to the envelope signal output end 131 for inputting an envelope signal provided by the envelope modulator 130. The reference potential terminal 115 is grounded, and the RF signal output terminal 117 is configured to output a second RF signal. The envelope modulator 130 may be an envelope modulator as described in any of the embodiments of FIG. 5, FIG. 8, FIG. 9, FIG. 11, or FIG.

Moreover, in one embodiment of the invention, an apparatus is also provided, which may be a communication device including an envelope tracking power amplifier 100 as described in the embodiment of FIG. The communication device may be a wireless base station.

The above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, and those skilled in the art can understand all or part of the process of implementing the above embodiments, and according to the claims of the present invention. Equivalent changes made are still within the scope of the invention.

Claims

An envelope modulator, comprising: an envelope amplifier, an operating voltage source and a floating voltage circuit, the envelope amplifier comprising an operating voltage input end, an envelope signal input end, a reference voltage input end, and an envelope signal output The positive pole of the working voltage source is electrically connected to the working voltage input end, the negative pole of the working voltage source is electrically connected to the reference voltage input end, and the floating voltage circuit is connected to the reference voltage input end. Between grounds for providing a reference voltage for the envelope amplifier, the envelope signal input for inputting a first envelope signal, the envelope amplifier for using the first envelope signal and the The reference voltage generates a second envelope signal, the envelope signal output for outputting the second envelope signal.
The envelope modulator of claim 1 wherein said floating voltage circuit comprises a first voltage source, said anode of said first voltage source being electrically coupled to said reference voltage input, said first voltage The negative pole of the source is grounded, and the reference voltage is equal to the voltage of the first voltage source.
The envelope modulator of claim 2, wherein the floating voltage circuit further comprises a second voltage source to an nth voltage source and a first switch to an nth switch, the first voltage source The positive electrode is electrically connected to the reference voltage input terminal through the first switch tube, and the positive electrode of the kth voltage source is electrically connected to the reference voltage input terminal through the kth switch tube, and the negative electrode of the kth voltage source and the kth -1 positive connection of a voltage source, where n is a positive integer greater than or equal to 2, and k is a positive integer greater than or equal to 2 and less than or equal to n.
The envelope modulator according to claim 3, wherein said first switching transistor is turned on, and the remaining switching transistors are turned off, said reference voltage being equal to a voltage of said first voltage source; said kth switching transistor Turning on, the remaining switches are turned off, and the reference voltage is equal to a sum of voltages of the k voltage sources of the first voltage source to the kth voltage source.
The envelope modulator according to claim 3 or 4, wherein said nth voltage source is said operating voltage source, said envelope modulator further comprising a first diode and a second diode First electric And a second capacitor, wherein a positive electrode of the nth voltage source is connected to a positive electrode of the first diode and an anode of the second diode, and a negative electrode of the nth voltage source and a voltage of the n-1th a positive electrode of the source is connected, a negative electrode of the first diode is connected to the working voltage input end, and a negative electrode of the second diode is connected to the reference voltage input end through an nth switch tube, the first A capacitor is connected between the working voltage input terminal and the reference voltage input terminal, and the second capacitor is connected between a cathode of the second diode and a positive pole of the n-1th voltage source.
The envelope modulator of claim 2, wherein the floating voltage circuit further comprises a second voltage source to an nth voltage source and a first switch to an nth switch, the first voltage source a positive electrode is electrically connected to the reference voltage input terminal through the first switch tube, and a positive electrode of the kth voltage source is electrically connected to the reference voltage input terminal through a kth switch tube, a negative pole of the kth voltage source and the The positive electrode of the first voltage source is connected, wherein n is a positive integer greater than or equal to 2, and k is a positive integer greater than or equal to 2 and less than or equal to n.
The envelope modulator according to claim 6, wherein said first switching transistor is turned on, the remaining switching transistors are turned off, said reference voltage is equal to a voltage of said first voltage source; said kth switching transistor Turning on, the remaining switches are turned off, and the reference voltage is equal to a sum of a voltage of the first voltage source and a voltage of the kth voltage source.
The envelope modulator according to claim 6 or 7, wherein said nth voltage source is said operating voltage source, said envelope modulator further comprising a first diode and a second diode a first capacitor and a second capacitor, wherein a positive electrode of the nth voltage source is connected to a positive electrode of the first diode and an anode of the second diode, and a negative electrode of the nth voltage source is a positive electrode of the first voltage source is connected, a negative electrode of the first diode is connected to the working voltage input end, and a negative electrode of the second diode is connected to the reference voltage input end through an nth switch tube. The first capacitor is connected between the operating voltage input terminal and the reference voltage input terminal, and the second capacitor is connected between the cathode of the second diode and the anode of the first voltage source.
An envelope modulator according to any of claims 3-8, wherein said floating battery The voltage circuit further includes a first driver to an nth driver, each of the switch transistors including a gate, a source and a drain, and a gate of the first switch is connected to the first driver, the first switch a source of the tube is connected to the anode of the first voltage source, a drain of the first switch tube is connected to the reference voltage input end, and a gate of the kth switch tube is connected to the kth driver, A source of the kth switch transistor is connected to the reference voltage input terminal, and a drain of the kth switch transistor is connected to an anode of the kth voltage source.
The envelope modulator according to claim 9, wherein a reference voltage of said first driver is equal to a voltage of said first voltage source, and a reference voltage of said kth driver is equal to a reference of said reference voltage input terminal The voltage varies with the change in the reference voltage.
An envelope tracking power amplifier, comprising a radio frequency power amplifier, characterized in that the envelope tracking power amplifier further comprises an envelope modulator according to any one of claims 1 to 10, the envelope modulator and The RF power amplifier is coupled to provide an envelope signal for the RF power amplifier.
A communication device comprising the envelope tracking power amplifier of claim 11.