A series-parallel type switch linear composite envelope tracking power supply

Abstract

This invention discloses a series-parallel type switched linear composite envelope tracking power supply, comprising a multilevel converter (VSC), a linear amplifier (VLA), and a switching converter (CSC). The multilevel converter (VSC) and the linear amplifier (VLA) are connected in series, and the switching converter (CSC) and the linear amplifier (VLA) are connected in parallel. The multilevel converter (VSC) tracks the envelope signal and outputs a stepped-wave voltage to fit the load voltage v. o Simultaneously, the stepped waveform voltage output by VSC serves as the input voltage of CSC; the linear amplifier VLA realizes the load voltage v o For the reference signal v ref The switching converter (CSC) outputs current to match the load current. This invention significantly reduces the switching frequency of the CSC and the voltage stress on the switching transistor without increasing the complexity of the series-parallel ET power supply, thereby improving the overall efficiency of the ET power supply.

Description

Technical Field

[0001] This invention belongs to the field of ET power supply technology, specifically relating to a series-parallel type switching linear composite envelope tracking power supply. Background Technology

[0002] Since its introduction in the 1970s, mobile communication has experienced rapid development from 1G to 5G due to its advantages such as flexibility and real-time performance. Second-generation (2G) mobile communication technology changed its modulation method from analog to digital, primarily using Time Division Multiple Access (TDMA) and Frequency Division Multiple Access (FDMA) digital cellular technologies. These modulation techniques only modulate the phase and frequency of the radio frequency (RF) signal, while keeping the amplitude constant. Therefore, a high-efficiency nonlinear power amplifier (NLPA) powered by constant voltage can be used to amplify the RF signal.

[0003] From the third to the fifth generation of mobile communication, more efficient modulation methods such as Code Division Multiple Access (CDMA) and Orthogonal Frequency Division Multiplexing (OFDM) were adopted to improve data transmission efficiency and spectrum utilization. At this time, the amplitude of the RF signal also began to carry the signal, no longer remaining constant but varying over time, exhibiting a larger peak-to-average power ratio (PAPR). To ensure the linearity of the RF signal, a linear power amplifier (LPA) is needed to amplify the RF signal. If a constant voltage power supply is still used, the LPA will experience a large voltage difference, leading to a decrease in PA efficiency. Therefore, research on how to improve LPA efficiency has received widespread attention both domestically and internationally.

[0004] To improve power amplifier efficiency, envelope tracking (ET) technology was proposed. In this technology, the power modulator is called the ET power supply. Its output voltage tracks the shaped envelope signal, amplifies its amplitude and power, and then serves as the drain supply voltage for the LPA. Since the ET power supply and LPA operate in a cascaded mode, the efficiency of the power amplifier system based on ET technology is affected by the efficiency of the ET power supply. Furthermore, the ET power supply must ensure tracking performance of the RF signal envelope to guarantee high efficiency for the LPA as well. Switch-Linear Hybrid (SLH) ET power supplies combine the high efficiency of switching converters with the high bandwidth of linear amplifiers, and have become the main structure for ET power supplies. Among them, series-parallel SLH ET power supplies can simultaneously reduce the voltage and output current of the linear amplifier, thus achieving high efficiency. In a typical series-parallel SLH ET power supply, the current-controlled switched-mode converter (CSC) operating in current source form is usually a Buck converter with hysteresis current control. With the increase of envelope bandwidth and PAPR, the range of load current change rate is larger. Because the Buck converter only has V... in The CSC operates at two voltage levels, zero and zero, resulting in a poor fit between the chopping point voltage and the load voltage. To match the rate of change of the inductor current with the rate of change of the load current, the switching frequency of the CSC becomes higher, thereby reducing system efficiency. Summary of the Invention

[0005] The technical problem this invention aims to solve is to address the shortcomings of the prior art by providing a series-parallel type switched linear composite envelope tracking power supply. It proposes multiplexing the stepped-wave voltage output from a multi-level converter, which can be used not only as the input voltage for the upper and lower transistors of a linear amplifier to reduce losses, but also as the input voltage for the CSC (Cellular Controller). Thus, without increasing circuit complexity, by multiplexing the stepped-wave voltage, the CSC is transformed from a two-level Buck converter into a multi-level converter, achieving better fitting results, significantly reducing the switching frequency of the CSC, and improving the overall efficiency of the ET (Electronic Power Supply). This invention is applied to power supplies for RF power amplifiers in wireless communication. VSC1 and VSC2 not only reduce VLA (Voltage Amplifier) ​​losses, but their output voltages can also be used as the chopper point voltage in the CSC, thereby improving the fitting effect of the chopper point voltage to the load voltage, significantly reducing the switching frequency of the CSC, and improving the overall efficiency of the ET power supply.

[0006] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0007] A series-parallel type switched linear composite envelope tracking power supply includes a multilevel converter (VSC), a linear amplifier (VLA), and a switching converter (CSC). The multilevel converter (VSC) is connected in series with the linear amplifier (VLA), and the switching converter (CSC) is connected in parallel with the linear amplifier (VLA).

[0008] The multilevel converter VSC tracks the envelope signal and outputs a stepped-wave voltage to fit the load voltage v. o Meanwhile, the stepped wave voltage output by VSC serves as the input voltage of CSC;

[0009] The linear amplifier VLA achieves the load voltage v o For the reference signal v ref Tracking;

[0010] The switching converter CSC outputs current to fit the load current.

[0011] To optimize the above technical solution, the specific measures also include:

[0012] The aforementioned multilevel converter VSC operates in voltage source mode, the linear amplifier VLA operates in voltage source mode and uses voltage closed-loop control, and the switching converter CSC operates in current source mode and uses hysteresis current control.

[0013] The linear amplifier VLA mentioned above is a Class A or Class AB linear amplifier.

[0014] When VLA is a Class AB linear amplifier, the multilevel converter VSC includes a first multilevel converter VSC1 and a second multilevel converter VSC2; when VLA is a Class AB linear amplifier, the multilevel converter VSC is the first multilevel converter VSC1.

[0015] Both VSC1 and VSC2 mentioned above include a level generation stage and a level gating stage; the level generation stage converts the input voltage into multiple levels with different amplitudes, and the level gating stage selects the level through a gating transistor and a blocking diode to fit the load voltage.

[0016] The level generation stage of VSC1 is implemented using a multi-channel Buck converter, while the level generation stage of VSC2 is implemented using a multi-channel Boost converter.

[0017] The aforementioned linear amplifier VLA includes a power transistor, a voltage sampling unit, and a voltage regulator; the voltage sampling unit measures the load voltage v through a voltage divider resistor. o After sampling, compared with the reference voltage v ref The comparison is performed, and the error signal is sent to the voltage regulator. The output of the voltage regulator drives the power transistor, thereby achieving V o For the reference signal vref Tracking.

[0018] The aforementioned CSC is composed of a Buck converter, including the switching transistor Q. CSC Freewheeling diode D f and filter inductor L f ; Switching transistor Q CSC The drain is connected to the output of VSC1, and the freewheeling diode D... f The anode is connected to the output of VSC2, and the switching transistor Q... CSC The source and freewheeling diode D f The cathode is connected as a filter inductor L. f Input voltage on one side, filter inductor L f The other side is connected to the load.

[0019] The present invention has the following beneficial effects:

[0020] This invention significantly reduces the switching frequency and switching transistor voltage stress of the CSC without increasing the complexity of the series-parallel ET power supply, thereby improving the overall efficiency of the ET power supply.

[0021] The series-parallel switching linear composite ET power supply structure proposed in this invention can significantly improve the fitting effect of the CSC chopper point voltage to the load voltage, thereby reducing the difference between the two, significantly reducing the switching frequency of the switching transistor in the CSC, and effectively improving the system efficiency.

[0022] In the CSC of this invention, after the switching transistor is turned off, the voltage across its terminals is the difference between the output voltages of the two multilevel converters, i.e., vVSC1-vVSC2. Therefore, the proposed series-parallel ET power supply can effectively reduce the voltage stress on the switching transistor and reduce switching losses. Attached Figure Description

[0023] Figure 1 The circuit of the series-parallel switch linear composite envelope tracking power supply of the present invention;

[0024] Figure 2 This is a circuit diagram of the multilevel converter in the tracking power supply of this invention;

[0025] Figure 3 This is a schematic diagram of the output of the VSC multilevel converter;

[0026] Figure 4 Typical waveforms for CSC when using hysteresis current control;

[0027] Figure 5 Equivalent circuit for tracking the four operating modes of the power supply;

[0028] Figure 6 This is a schematic diagram of the key points of the converter CSC in this invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0030] Although the steps in this invention are arranged by reference numerals, this is not intended to limit the order of the steps. Unless the order of the steps is explicitly stated or the execution of a step requires other steps as a basis, the relative order of the steps can be adjusted. It is understood that the term "and / or" as used herein refers to and covers any and all possible combinations of one or more of the associated listed items.

[0031] like Figure 1 As shown, the present invention employs a series-parallel type switch linear composite envelope tracking power supply, including a multilevel converter VSC, a linear amplifier VLA, and a switch converter CSC. The multilevel converter VSC is connected in series with the linear amplifier VLA, and the switch converter CSC is connected in parallel with the linear amplifier VLA.

[0032] The multilevel converter VSC operates in voltage source mode, tracks the envelope signal, and outputs a stepped-wave voltage to fit the load voltage v. o This reduces the voltage across the VLA, improves its efficiency, and thus reduces its losses. At the same time, the output voltage of the VSC serves as the chopping point voltage of the CSC, making it better fit the load voltage (improving the fitting effect to the load voltage), thereby reducing the switching frequency of the CSC and resulting in a lower equivalent switching frequency.

[0033] The linear amplifier VLA operates in voltage source mode, employing voltage closed-loop control to track the radio frequency envelope signal and achieve the load voltage v. o For the reference signal v ref Tracking enables high tracking bandwidth for ET power supplies.

[0034] In this embodiment, the linear amplifier VLA can be a Class A or Class AB linear amplifier. When the VLA is a Class AB linear amplifier, the multilevel converter VSC is the first multilevel converter VSC1. When a Class AB VLA is used, there are two sets of multilevel converters VSC1 and VSC2.

[0035] The linear amplifier VLA includes an output power transistor, a voltage sampling unit, and a voltage regulator; the voltage closed-loop control refers to the voltage sampling unit controlling the load voltage V through a voltage divider resistor. o After sampling, compared with the reference voltage v ref The comparison is performed, and the error signal is sent to the voltage regulator. The output of the voltage regulator drives the output power transistor, thereby achieving Vo For the reference signal v ref Tracking.

[0036] The CSC is composed of a Buck converter, including a switching transistor Q. CSC Freewheeling diode D f and filter inductor L f ; Switching transistor Q CSC The drain can be connected to the output of VSC1, and the freewheeling diode D... f The anode is connected to the output of VSC2, and the switching transistor Q... CSC The source and freewheeling diode D f The cathode is connected, serving as the input voltage on one side of the inductor, while the other side is connected to the load. In the CSC, the inductor current is fitted to the load current to reduce the VLA output current.

[0037] like Figure 1 As shown in (a), VLA uses a Class A linear amplifier, and the output of VSC1 is connected not only to VLA, but also to the CSC switching transistor Q. CSC The drain connection, freewheeling diode D f Connected to the ground. For example... Figure 1 As shown in (b), VLA uses a Class AB linear amplifier with an added multilevel converter VSC2, whose output is connected to the power transistor Q of VLA. d and freewheeling diode D f Anode connection.

[0038] like Figure 2 As shown, VSC1 and VSC2 include a level generation stage and a level gating stage. Figure 2 The level generation stage in VSC1 uses a multi-channel Buck converter to convert the input voltage V... in Converted to multiple different amplitude levels V iu (V 1u <V 2u <… <V mu The gating transistor in the level selection stage will select the reference signal v. ref By comparing with multiple levels of different amplitudes, the corresponding level selector SW is obtained. 2u ~SW mu The control signal blocks diode D. iu (i = 1, 2, ..., m-1) is used to avoid direct paralleling of voltage sources with different amplitudes; Figure 2 The level generation stage of VSC2 is constructed using a multi-channel Boost converter, outputting levels V of different amplitudes. id (V 1d <V 2d <… <V nd The level selection stage is also composed of the selection transistor SW. id(i = 1, 2, ..., n-1) and blocking diode D id Composed of (i = 2, 3, ..., n), a suitable voltage is selected to fit the load voltage; both VSC1 and VSC2 output stepped voltages to fit v. o The output v of VSC1 VSC1 Used to reduce Figure 1 China Q u The voltage it withstands is always greater than v. o The output v of VSC2 VSC2 Used to reduce Figure 1 China Q d The voltage it withstands is always less than V. o The waveforms of both are as follows Figure 3 As shown.

[0039] In the embodiments, such as Figure 4 The following are typical waveforms of CSC using hysteresis current control, combined with... Figure 4 The specific modes of the structure proposed in this invention under hysteresis current control are as follows:

[0040] According to i CSC and i o Based on the changes in these conditions, the operating modes of the ET power supply of this invention can be divided into the following four cases:

[0041] Case I: At time t1, i CSC ≤i o -0.5·Δi, i should be increased CSC To reduce i VLA Therefore, the switching transistor Q CSC When switched on, the inductor voltage becomes v. VSC1 -v o >0, i CSC It begins to rise. In this mode, due to i CSC o power transistor Q u On, for i o Compensation is performed. The modal equivalent circuit is as follows: Figure 5 As shown in (a), the multilevel converter VSC1 provides power to both VLA and CSC at the same time.

[0042] Case II: At time t2, i CSC Q continues to rise within the ring width. CSC The circuit remains open. However, at time t2, i... CSC >i o Therefore Q d When the circuit is turned on, excess current flows through Q. d Then, the signal is fed back to the input via VSC2. The modal equivalent circuit is as follows: Figure 5 ​As shown in (b), VSC1 provides power to CSC only, while VSC2 operates in Boost mode to absorb power.

[0043] Case III: At time t3, i CSC ≥i o +0.5·Δi, Q CSC When the circuit is turned off, the inductor voltage is v. VSC2 -v o <0, i CSC Start to decrease in order to reduce Q d Loss. In this mode, i CSC >i o Q d The circuit remains open, and the current i flowing through it is... VLA =i CSC –i o It can be known that Q d Absorbed current i VLA CSC Therefore i VLA It flows back to CSC. The modal equivalent circuit is as follows: Figure 5 As shown in (c), VSC2 operates in Buck mode to provide power to CSC.

[0044] Case IV: At time t4, i CSC o Q u It works to compensate for load current. And i CSC Q continues to decrease within the ring width. CSC Maintain the off state. The modal equivalent circuit is as follows: Figure 5 As shown in (d), VSC1 provides power to VLA only, and VSC2 provides power to CSC.

[0045] Figure 6 The key waveforms of the series-parallel switching linear composite envelope tracking power supply proposed in this invention are given. When Q CSC When the circuit is turned on, the voltage on one side of the inductor is v. VSC1 It fits v better o That is, the voltage across the inductor of the CSC is reduced; in Q CSC When turned off, the voltage on one side of the inductor is v. VSC2 It fits v better o This means that the voltage across the inductor of the CSC is reduced. Therefore, v VSC1 and v VSC2 Both are used as the chopper point voltage of CSC, making v CSC It can fit v very well o Therefore Q CSC The switching frequency is significantly reduced, and this scheme can also reduce Q. CSC ​​Voltage stress effectively improves the overall efficiency of the ET power supply.

[0046] The main performance parameters of a specific embodiment of the present invention are: reference signal v ref 20MHz LTE; Input voltage: 30V; Output voltage: V o : 9V~27V; PAPR: 6.3dB.

[0047] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0048] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A series-parallel type switched linear composite envelope tracking power supply, characterized in that, It includes a multilevel converter (VSC), a linear amplifier (VLA), and a switching converter (CSC), wherein the multilevel converter (VSC) is connected in series with the linear amplifier (VLA), and the switching converter (CSC) is connected in parallel with the linear amplifier (VLA). The multilevel converter VSC tracks the envelope signal and outputs a stepped-wave voltage to fit the load voltage v. o Meanwhile, the stepped wave voltage output by VSC serves as the input voltage of CSC; The linear amplifier VLA achieves the load voltage v o For the reference signal v ref Tracking; The switching converter CSC outputs current to fit the load current; The linear amplifier VLA is a Class A or Class AB linear amplifier. When VLA is a Class AB linear amplifier, the multilevel converter VSC includes a first multilevel converter VSC1 and a second multilevel converter VSC2. When VLA is a Class A linear amplifier, the multilevel converter VSC is the first multilevel converter VSC1. Both VSC1 and VSC2 include a level generation stage and a level gating stage; the level generation stage converts the input voltage into multiple levels with different amplitudes, and the level gating stage selects the level through a gating transistor and a blocking diode to fit the load voltage. The level generation stage of VSC1 is implemented using a multi-channel Buck converter, and the level generation stage of VSC2 is implemented using a multi-channel Boost converter. The CSC is composed of a Buck converter, including a switching transistor Q. CSC Freewheeling diode D f and filter inductor L f ; Switching transistor Q CSC The drain is connected to the output of VSC1, and the freewheeling diode D... f The anode is connected to the output of VSC2, and the switching transistor Q... CSC The source and freewheeling diode D f The cathode is connected, serving as the filter inductor L. f Input voltage on one side, filter inductor L f The other side is connected to the load.

2. The series-parallel type switch linear composite envelope tracking power supply according to claim 1, characterized in that, The multilevel converter VSC operates in voltage source mode, the linear amplifier VLA operates in voltage source mode and uses voltage closed-loop control, and the switching converter CSC operates in current source mode and uses hysteresis current control.

3. A series-parallel type switch linear composite envelope tracking power supply according to claim 1, characterized in that, The linear amplifier VLA includes a power transistor, a voltage sampling unit, and a voltage regulator; the voltage sampling unit measures the load voltage V through a voltage divider resistor. o After sampling, compared with the reference voltage v ref The comparison is performed, and the error signal is sent to the voltage regulator. The output of the voltage regulator drives the power transistor, thereby achieving V... o For the reference signal v ref Tracking.

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