Radio frequency amplifier circuit with fast response rate

Abstract

The invention discloses a radio frequency amplifier circuit with a fast response rate, and relates to the technical field of radio frequency amplifiers. A bias point of the radio frequency amplifier is grounded, an equivalent capacitor is connected between the bias point and the equivalent capacitor is the sum of all capacitors at the bias point and comprises a blocking capacitor and a parasitic capacitor; a first bias resistor and a second bias resistor are connected in parallel between the bias point and the equivalent capacitor, the first bias resistor and the second bias resistor are arranged in series, and first switches are arranged at two ends of the second bias resistor; and / or a second switch is connected in parallel between the equivalent capacitor and the radio frequency amplifier. According to the invention, the bias resistance value is temporarily reduced or the bias voltage is increased in a period from starting to stabilization, the performance of the amplifier after stable work is not influenced, the response rate is higher, the final signal amplitude is not influenced, and the performance of the amplifier is not influenced.

Description

Technical Field

[0001] The invention belongs to the technical field of radio frequency amplifiers, and in particular relates to a radio frequency amplifier circuit with a fast response rate. Background Art

[0002] In mobile communication applications, the response time of the transceiver system is an important performance in time-division communication, which enables the signal to be transmitted faster and more efficiently in communication. In order to improve the response rate of the transceiver system, it is necessary to further study how to improve the response speed of important integrated parts in the transceiver system.

[0003] like Figure 1 The figure shows the structure of a traditional RF amplifier, which includes an RF amplifier connected between an input terminal IN and an output terminal OUT. The existing solution accelerates the response by adjusting the bias resistor R or the equivalent capacitor C at point "X", but it will deteriorate the basic amplifier performance such as the input and output return loss and transmission gain of the circuit; one of the main factors affecting the response rate of the RF amplifier is the size of the RC time constant and the bias voltage at the amplifier bias point (X). As long as the RC time constant is reduced by adjusting the bias resistor R and the equivalent capacitor C, or the bias voltage is increased during the period from the start-up of the amplifier to the stabilization, the charging state of the RF amplifier can be accelerated to achieve a stable working state.

[0004] The above-mentioned prior art mainly adjusts the equivalent capacitance C and the bias resistor R, but blindly reducing the capacitance and resistance values ​​will deteriorate the basic amplifier performance such as the input and output return loss and transmission gain of the circuit, which has little effect and high risk. The present technical solution provides a radio frequency amplifier circuit with a fast response rate, which only temporarily reduces the bias resistance value or increases the bias voltage during the startup to stabilization period, and does not affect the performance of the amplifier after stable operation. Summary of the invention

[0005] The present invention provides a radio frequency amplifier circuit with a fast response rate, such as Figure 2As shown, before the amplifier works stably, R2 is briefly short-circuited through SW to reduce the RC time constant from startup to stabilization, thereby improving the amplifier response rate; and / or, the bias voltage of the amplifier bias point is briefly pulled to a high level VH through SW, so that the amplifier can be quickly charged to achieve stability, thereby improving the response rate of the entire amplifier; SW can be controlled on and off by a pulse signal sent by the controller, and the pulse signal is only at a high level before the amplifier works stably, and is at a low level for the rest of the time; the type of controller is not unique; compared with the traditional RF amplifier circuit, this solution only temporarily reduces the bias resistance value or increases the bias voltage from startup to stabilization, and does not affect the performance of the amplifier after stable operation, has a faster response rate, and does not affect the final signal amplitude, and the performance of the amplifier is not affected; in summary, the above problems are solved.

[0006] In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

[0007] A radio frequency amplifier circuit with a fast response rate of the present invention comprises a radio frequency amplifier;

[0008] The bias point of the radio frequency amplifier is grounded and connected with an equivalent capacitor in the middle, wherein the equivalent capacitor is the sum of all capacitors at the bias point, including a DC blocking capacitor and a parasitic capacitor;

[0009] A bias resistor is connected in parallel between the bias point and the equivalent capacitor, and a second switch is connected in parallel between the equivalent capacitor and the RF amplifier; and / or, the bias resistor includes a first bias resistor and a second bias resistor, the first bias resistor and the second bias resistor are arranged in series, the other end of the second bias resistor is connected to the bias voltage, and a first switch is provided at both ends of the second bias resistor.

[0010] Furthermore, the resistance of the first bias resistor is smaller than that of the second bias resistor, and the second bias resistor is temporarily short-circuited by the first switch before the RF amplifier operates stably, thereby reducing the RC time constant from startup to stabilization.

[0011] Furthermore, the bias voltage of the radio frequency amplifier is briefly pulled to a high level through the second switch; the high level is greater than the bias voltage.

[0012] Furthermore, the first switch and the second switch are both controlled to be on and off by sending a pulse signal through the controller, and the pulse signal is at a high level only before the RF amplifier works stably, and is at a low level at other times.

[0013] Furthermore, the controller adopts a CPU, a central processing unit, an MCU or an FPGA.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] (1) This solution briefly short-circuits R2 through SW before the amplifier operates stably, thereby reducing the RC time constant from startup to stabilization, thereby improving the amplifier response rate; and / or, briefly pulls the bias voltage of the amplifier bias point to a high level VH through SW, thereby allowing the amplifier to charge quickly to reach stability, thereby improving the overall amplifier response rate;

[0016] (2) The SW of this solution can be controlled on and off by the pulse signal sent by the controller. The pulse signal is high level only before the amplifier works stably, and is low level at other times. The type of controller is not unique.

[0017] (3) Compared with the traditional RF amplifier circuit, this solution only temporarily reduces the bias resistance value or increases the bias voltage during the period from startup to stabilization, which does not affect the performance of the amplifier after stable operation. It has a faster response rate and does not affect the final signal amplitude. The performance of the amplifier is not affected.

[0018] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0020] Figure 1 It is a structural diagram of a traditional RF amplifier;

[0021] Figure 2 This is a circuit structure diagram of a radio frequency amplifier with a fast response rate according to a specific embodiment 1 of the present invention;

[0022] Figure 3 This is a circuit structure diagram of a radio frequency amplifier with a fast response rate according to a specific embodiment 2 of the present invention;

[0023] Figure 4 This is a circuit structure diagram of a radio frequency amplifier with a fast response rate according to a specific embodiment 3 of the present invention;

[0024] Figure 5 This is a simulation comparison diagram of startup time of a traditional RF amplifier and three amplifiers of this specific embodiment;

[0025] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0026] C-equivalent capacitance, X-bias point, VDD-supply voltage, VH-high level, Vb-bias voltage, AMP-RF amplifier, R-bias resistor, R1-first bias resistor, R2-first bias resistor, where R=R1+R2, SW1-first switch, SW2-second switch, IN-input, OUT-output. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Conventional RF amplifiers such as Figure 1 As shown, the main thing is to adjust the equivalent capacitance C and the bias resistor R. However, blindly reducing the capacitance and resistance values ​​will deteriorate the basic performance of the amplifier such as the input and output return loss and transmission gain of the circuit, with little effect and high risk.

[0029] This solution only temporarily reduces the bias resistance value or increases the bias voltage during the startup to stabilization period, and does not affect the performance of the amplifier after it stabilizes. It is implemented through the following specific solutions: Specific embodiment 1:

[0031] See also Figure 2 As shown, a radio frequency amplifier circuit with a fast response rate of the present invention includes a radio frequency amplifier AMP; a bias point X of the radio frequency amplifier AMP is grounded and an equivalent capacitor C is connected in the middle, and the equivalent capacitor C is the sum of all capacitors at the bias point X, including a DC blocking capacitor and a parasitic capacitor;

[0032] A first bias resistor R1 and a second bias resistor R2 are connected in parallel between the bias point X and the equivalent capacitor C. The first bias resistor R1 and the second bias resistor R2 are arranged in series. The other end of the second bias resistor R2 is connected to the bias voltage Vb. A first switch SW1 is arranged at both ends of the second bias resistor R2.

[0033] In this embodiment, Figure 1 The bias resistor R in the traditional RF amplifier circuit is split into two resistors R1 and R2. The first bias resistor R1 and the second bias resistor R2 are connected in series. The first bias resistor R1 is kept as small as possible. Before the amplifier works stably, R2 is short-circuited briefly through SW1 to reduce the RC time constant from startup to stabilization, thereby improving the amplifier response rate. Specific embodiment 2:

[0035] See also Figure 3 As shown, a radio frequency amplifier circuit with a fast response rate of the present invention includes a radio frequency amplifier AMP; a bias point X of the radio frequency amplifier AMP is grounded and an equivalent capacitor C is connected in the middle, the equivalent capacitor C is the sum of all capacitors at the bias point X, including a DC blocking capacitor and a parasitic capacitor, a bias resistor R is connected in parallel between the bias point X and the equivalent capacitor C, the other end of R is connected to a bias voltage Vb, and a second switch SW2 is connected in parallel between the equivalent capacitor C and the radio frequency amplifier AMP; the bias voltage of the bias point of the radio frequency amplifier AMP is briefly pulled to a high level VH (VH>bias voltage Vb) through the second switch SW2, so that the amplifier is quickly charged to reach stability, thereby improving the response rate of the entire amplifier; Specific embodiment 3:

[0037] See also Figure 4 As shown, by combining the structures of specific embodiment 1 and specific embodiment 2, a radio frequency amplifier circuit with a fast response rate of the present invention includes a radio frequency amplifier AMP; the bias point X of the radio frequency amplifier AMP is grounded and an equivalent capacitor C is connected in the middle, and the equivalent capacitor C is the sum of all capacitors at the bias point X, including a DC blocking capacitor and a parasitic capacitor; a first bias resistor R1 and a second bias resistor R2 are connected in parallel between the bias point X and the equivalent capacitor C, the first bias resistor R1 and the second bias resistor R2 are arranged in series, the other end of the second bias resistor R2 is connected to a bias voltage Vb, and a first switch SW1 is provided at both ends of the second bias resistor R2;

[0038] A second switch SW2 is connected in parallel between the equivalent capacitor C and the RF amplifier AMP; the bias voltage of the bias point of the RF amplifier AMP is briefly pulled to a high level VH (VH> bias voltage Vb) through the second switch SW2, so that the amplifier is quickly charged to reach stability, thereby improving the response rate of the entire amplifier;

[0039] Since the key point of this solution is to improve the response rate by temporarily reducing the equivalent RC time constant of the circuit bias point or temporarily raising the bias voltage of the circuit bias point, in order to adapt to different circuit structures, the bias points of different structures are collectively referred to as point "X", C represents the sum of all capacitors and parasitic capacitors at point "X", and the control signal of the first switch SW1 / the second switch SW2 is a pulse signal;

[0040] The resistance of the first bias resistor R1 is smaller than that of the second bias resistor R2. Before the RF amplifier AMP works stably, the second bias resistor R2 is short-circuited temporarily through the first switch SW1 to reduce the RC time constant from startup to stabilization.

[0041] The first switch SW1 and the second switch SW2 are both controlled to be on and off by sending a pulse signal through the controller. The pulse signal is at a high level only before the RF amplifier AMP works stably, and is at a low level at other times.

[0042] Figure 2 / Figure 3 Both implementation methods can be used or only one of them can be used according to the actual situation.

[0043] The first switch SW1 and the second switch SW2 can be turned on and off by a pulse signal sent by the controller. The pulse signal is high level only before the amplifier works stably, and is low level at other times. The type of controller is not unique, for example, it can be a CPU (Central Processing Unit), an MCU (Microcontroller Unit), an FPGA (Field-Programmable Gate Array), and other devices.

[0044] For detailed description and demonstration, in this specific embodiment, the blocking capacitor C=7pF, the bias resistor R=37K (where R1=6K, R2=31K);

[0045] Figure 4 Given the situation where this solution is not used, Figure 1 A traditional RF amplifier structure, and a startup time simulation diagram of the RF amplifier using specific embodiment 1, specific embodiment 2, and specific embodiment 3 respectively; it can be seen from the figure that the RF amplifiers all send an enable signal at 1us to start working, the amplifier startup time of the amplifier not using this solution is 0.86us, and the startup times of the other three amplifiers are 0.7us, 0.61us, and 0.42us respectively. The amplifier can respond faster without affecting the final signal amplitude, and the performance of the amplifier is not affected.

[0046] The amplifier circuit described in this solution is not limited to MOS transistor circuits, but also applicable to BJT transistor circuits. The gate of the corresponding MOS transistor is the base of the BJT transistor, and it can be applied according to actual needs. At the same time, this solution is also applicable to other RF circuits and analog circuits, as long as the main bias point (X) that affects the response time of the circuit is found, and the RC constant or bias voltage of the bias point (X) is adjusted through this solution.

[0047] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A radio frequency amplifier circuit with a fast response rate, comprising a radio frequency amplifier (AMP), characterized in that: The bias point (X) of the radio frequency amplifier (AMP) is grounded and has an equivalent capacitor (C) in between, wherein the equivalent capacitor (C) is the sum of all capacitors at the bias point (X), including a DC blocking capacitor and a parasitic capacitor; A bias resistor (R) is connected in parallel between the bias point (X) and the equivalent capacitor (C), and a second switch (SW2) is connected in parallel between the equivalent capacitor (C) and the radio frequency amplifier (AMP); and / or the bias resistor (R) includes a first bias resistor (R1) and a second bias resistor (R2), the first bias resistor (R1) and the second bias resistor (R2) are arranged in series, the other end of the second bias resistor (R2) is connected to a bias voltage (Vb), and a first switch (SW1) is provided at both ends of the second bias resistor (R2).

2. The radio frequency amplifier circuit with a fast response rate according to claim 1, characterized in that: The resistance of the first bias resistor (R1) is smaller than that of the second bias resistor (R2). Before the radio frequency amplifier (AMP) works stably, the second bias resistor (R2) is short-circuited temporarily through the first switch (SW1) to reduce the RC time constant from startup to stabilization.

3. The radio frequency amplifier circuit with a fast response rate according to claim 1, characterized in that: The bias voltage (Vb) of the radio frequency amplifier (AMP) is briefly pulled to a high level (VH) through the second switch (SW2); the high level (VH) is greater than the bias voltage (Vb).

4. The radio frequency amplifier circuit with a fast response rate according to claim 1, characterized in that: The first switch (SW1) and the second switch (SW2) are both controlled to be on and off by sending a pulse signal through a controller, and the pulse signal is at a high level only before the radio frequency amplifier (AMP) works stably, and is at a low level at other times.

5. The radio frequency amplifier circuit with a fast response rate according to claim 4, characterized in that: The controller adopts CPU, central processing unit, MCU or FPGA.

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