Adaptive impedance adjustment circuit

Abstract

The present invention discloses an adaptive impedance adjustment circuit, comprising a power amplifier, a directional coupler and a control logic circuit connected in sequence, the adaptive impedance adjustment circuit also comprises an impedance tuning circuit, a first power detector and a second power detector, the output end of the power amplifier is connected to the input end of the impedance tuning circuit, the output end of the impedance tuning circuit is connected to the input end of the directional coupler, the output end of the directional coupler is used to connect a load, the input end of the first power detector is connected to the output end of the power amplifier, the input end of the second power detector is connected to the output end of the directional coupler, the output end of the first power detector and the output end of the second power detector are respectively connected to the input end of the control logic circuit, and the output end of the control logic circuit is connected to the input end of the impedance tuning circuit. The adaptive impedance adjustment circuit of the present invention has strong anti-interference ability, high transmission efficiency and wide application range.

Description

[Technical field]

[0001] The present invention relates to the field of communication technology, and in particular to an adaptive impedance adjustment circuit. [Background technology]

[0002] As humans enter the information age, wireless communication technology has developed rapidly, from mobile phones, wireless LAN, Bluetooth, etc., which have become an indispensable part of social life and development. The progress of wireless communication technology is inseparable from the development of radio frequency circuits.

[0003] At present, in the RF circuit, the transceiver chip outputs a modulated signal to the input of the power amplifier, which amplifies the small input signal and outputs it; after impedance matching by the matching circuit, it is output to the load; the load can be an antenna or cable, etc. The matching circuit is used to achieve the best impedance matching between the amplifier output and the load, so that the signal energy can be transmitted to the maximum extent.

[0004] However, in actual use scenarios, the load impedance may not be fixed. For example, in mobile terminals such as mobile phones, the antenna impedance changes greatly with the change of the use environment; at this time, there will be an impedance mismatch between the power amplifier and the antenna, and the output energy of the power amplifier will be reflected back, resulting in poor anti-interference ability of the circuit, thereby greatly reducing the transmission efficiency of the RF circuit. [Summary of the invention]

[0005] The purpose of the embodiment of the present invention is to provide an adaptive impedance adjustment circuit to solve the problems of poor anti-interference ability and low transmission efficiency of the existing radio frequency circuit.

[0006] In order to solve the above technical problems, an embodiment of the present invention provides an adaptive impedance adjustment circuit, comprising a power amplifier, a directional coupler and a control logic circuit connected in sequence, the adaptive impedance adjustment circuit also includes an impedance tuning circuit, a first power detector and a second power detector, the output end of the power amplifier is connected to the input end of the impedance tuning circuit, the output end of the impedance tuning circuit is connected to the input end of the directional coupler, the output end of the directional coupler is used to connect a load, the input end of the first power detector is connected to the output end of the power amplifier, the input end of the second power detector is connected to the output end of the directional coupler, the output end of the first power detector and the output end of the second power detector are respectively connected to the input end of the control logic circuit, and the output end of the control logic circuit is connected to the input end of the impedance tuning circuit; the first power detector and the second power detector respectively detect the output signal of the power amplifier and the reverse signal reflected by the load to the directional coupler, and respectively convert the output signal and the reverse signal into a first DC voltage and a second DC voltage; the control logic circuit respectively receives the first DC voltage and the second DC voltage, and outputs a control signal to the impedance tuning circuit after common processing to achieve adaptive adjustment.

[0007] Preferably, the control logic circuit receives the first DC voltage and the second DC voltage, and calculates a reflection coefficient of the control signal; wherein the first DC voltage is defined as Vdet1, the second DC voltage is defined as Vdet2, and the reflection coefficient is R, R=Vdet2 / Vdet1.

[0008] Preferably, the reflection coefficient includes multiple and is R(n-1); the impedance tuning circuit includes multiple Tuner states and is Tu(n-1); wherein the multiple reflection coefficients correspond one-to-one to the multiple Tuner states, and n represents the number.

[0009] Preferably, the adaptive impedance adjustment circuit also includes an external main control circuit, the output end of the external main control circuit is connected to the input end of the control logic circuit, and the output end of the control logic circuit outputs the control signal to the impedance tuning circuit.

[0010] Preferably, the external main control circuit includes a first trigger unit and a second trigger unit. When the first trigger unit is in state one, the control logic circuit operates according to a preset timing. When the first trigger unit is in state two, the control logic circuit detects that the second trigger unit is in a specific state and performs a round of Tuner state polling and adjustment.

[0011] Preferably, the adaptive impedance adjustment circuit further includes an inter-stage matching circuit, the input end of the inter-stage matching circuit is connected to the output end of the power amplifier, and the output end of the inter-stage matching circuit is connected to the input end of the impedance tuning circuit.

[0012] Compared with the prior art, the adaptive impedance adjustment circuit in the present invention connects the output end of the impedance tuning circuit to the input end of the directional coupler, the output end of the directional coupler is used to connect the load, the input end of the first power detector is connected to the output end of the power amplifier, the input end of the second power detector is connected to the output end of the directional coupler, the output end of the first power detector and the output end of the second power detector are respectively connected to the input end of the control logic circuit, and the output end of the control logic circuit is connected to the input end of the impedance tuning circuit; the first power detector and the second power detector respectively detect the output signal of the power amplifier and the reverse signal reflected by the load to the directional coupler, and respectively convert the output signal and the reverse signal into a first DC voltage and a second DC voltage; the control logic circuit receives the first DC voltage and the second DC voltage respectively, and outputs a control signal to the impedance tuning circuit after common processing to achieve adaptive adjustment; thereby making the RF circuit adaptively adjustable and the impedance tuning circuit strong in anti-interference ability, thereby greatly improving the transmission efficiency of the RF circuit.

Brief Description of the Drawings

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0014] Figure 1 A module diagram of an adaptive impedance adjustment circuit provided by an embodiment of the present invention;

[0015] Figure 2 A timing diagram of an adaptive impedance adjustment circuit provided in an embodiment of the present invention.

[0016] Among them, 100, adaptive impedance adjustment circuit, 1, power amplifier, 2, impedance tuning circuit, 3, directional coupler, 4, load, 5, first power detector, 6, second power detector, 7, control logic circuit, 8, external main control circuit, 81, first trigger unit, 82, second trigger unit. [Specific implementation method]

[0017] The technical solutions in the embodiments of the present invention are described clearly and completely below. 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.

[0018] like Figure 1-2 As shown, an embodiment of the present invention provides an adaptive impedance adjustment circuit 100, comprising a power amplifier, a directional coupler 3 and a control logic circuit 7 connected in sequence, the adaptive impedance adjustment circuit 100 also includes an impedance tuning circuit 2, a first power detector 5 and a second power detector 6, the output end of the power amplifier is connected to the input end of the impedance tuning circuit 2, the output end of the impedance tuning circuit 2 is connected to the input end of the directional coupler 3, the output end of the directional coupler 3 is used to connect to a load 4, the input end of the first power detector 5 is connected to the output end of the power amplifier, the input end of the second power detector 6 is connected to the output end of the directional coupler 3, The output end of the first power detector 5 and the output end of the second power detector 6 are respectively connected to the input end of the control logic circuit 7, and the output end of the control logic circuit 7 is connected to the input end of the impedance tuning circuit 2; the first power detector 5 and the second power detector 6 respectively detect the output signal of the power amplifier and the reverse signal reflected by the load 4 to the directional coupler 3, and convert the output signal and the reverse signal into a first DC voltage and a second DC voltage respectively; the control logic circuit 7 receives the first DC voltage and the second DC voltage respectively, and outputs a control signal to the impedance tuning circuit 2 after common processing to achieve adaptive adjustment.

[0019] Specifically, the output end of the power amplifier outputs the amplified signal to the impedance tuning circuit 2, the impedance tuning is performed through the impedance tuning circuit 2, and the tuned amplified signal is output to the directional coupler 3 through the impedance tuning circuit 2. The directional coupler 3 couples the signal and outputs it to the load 4, which can be an antenna and a cable, etc., for realizing the function of the circuit load 4. The directional coupler 3 does not couple the forward output signal, but only couples the reverse signal reflected from the load 4. The reverse coupling signal is sent to the second power detector 6 for conversion into a second DC signal and sent to the control logic circuit 7. The first power detector 5 is used to detect the amplified signal output from the output end of the power amplifier, and convert the amplified signal into a first DC voltage, and send it to the control logic circuit 7. The control logic circuit 7 receives the first DC voltage and the second DC voltage, and after processing, the control signal is output to the impedance tuning circuit 2 to achieve the impedance matching effect between the power amplifier and the load 4. Thereby, the RF circuit is convenient for adaptive adjustment, and the impedance tuning circuit 2 has a strong anti-interference ability, thereby greatly improving the transmission efficiency of the RF circuit.

[0020] Optionally, the power amplifier is connected to the directional coupler 3 and the impedance tuning circuit 2 in sequence. In this way, the connection positions of the directional coupler 3 and the impedance tuning circuit 2 can also be interchanged, and the resulting function is the same as that of the impedance tuning circuit 2 connecting the directional coupler 3, which will not be described one by one here.

[0021] In this embodiment, the control logic circuit 7 receives the first DC voltage and the second DC voltage, and calculates the reflection coefficient of the control signal; wherein the first DC voltage is defined as Vdet1, the second DC voltage is defined as Vdet2, and the reflection coefficient is R, R=Vdet2 / Vdet1.

[0022] Among them, the reflection coefficient of the circuit can be calculated according to the values ​​of Vdet1 and Vdet2 by the control logic circuit 7, and then the mismatch degree of the load 4 can be determined. Since the modulus of the reflection coefficient is defined as R=Vdet2 / Vdet1, it is obvious that the higher the mismatch degree of the load 4, the stronger the reflected signal, and the larger R. The Tuner parameter (tuning parameter) of the impedance tuning circuit 2 is adjusted according to R by the control logic, and finally R is minimized to achieve the purpose of impedance matching between the amplifier and the load 4.

[0023] In this embodiment, the reflection coefficient includes multiple and is R(n-1); the impedance tuning circuit 2 includes multiple Tuner states and is Tu(n-1); wherein the multiple reflection coefficients correspond one-to-one to the multiple Tuner states, and n represents the number.

[0024] The impedance tuning circuit 2 may be an impedance tuner, which has n states, and the input and output impedances of each state are different; the value of n may be determined when the circuit is designed. The control logic circuit 7 has a corresponding table (or other forms such as a two-dimensional array) inside, which has 2 columns and n rows. As shown in the following table, the left column is the Tuner state, and the corresponding right column is the reflection coefficient R.

[0025] Tuner Status Reflection coefficient Tu0 R0 Tu1 R1 Tu2 R2 … … Tu(n-1) R(n-1)

[0026] When the circuit is powered on and works normally, the control logic circuit 7 starts, switches the Tuner state of the impedance tuning circuit 2 through the control signal, polls the n states of the Tuner, and reads the reflection coefficient R of the corresponding state and stores it in the table. After polling the R values ​​of all n states, the control logic compares the n R values ​​to obtain the minimum value R(m), and then obtains Tu(m)m≤n. In the following period of time, the control logic controls the Tuner to work in the Tu(m) state.

[0027] Since the terminal impedance may change during operation, the control logic circuit 7 detects the R value according to the preset timing T (T can be hundreds of ms or longer), and compares the reflection coefficient R with the preset reflection coefficient RLimit. If the reflection coefficient R>RLimit, a new round of polling begins, otherwise no polling is performed.

[0028] For example, T is 100ms, 200ms, etc.

[0029] In this embodiment, the adaptive impedance adjustment circuit 100 also includes an external main control circuit 8, the output end of the external main control circuit 8 is connected to the input end of the control logic circuit 7, and the output end of the control logic circuit 7 outputs the control signal to the impedance tuning circuit 2. The control logic circuit 7 receives the first DC voltage and the second DC voltage respectively, and outputs the control signal to the impedance tuning circuit 2 in combination with the received trigger signal of the external main control circuit 8, so as to realize adaptive adjustment. In this way, the control mode of the impedance tuning circuit 2 is diverse, so that the RF circuit is convenient for adaptive adjustment, and the impedance tuning circuit 2 has strong anti-interference ability, thereby greatly improving the transmission efficiency of the RF circuit.

[0030] In this embodiment, the external main control circuit 8 includes a first trigger unit 81 and a second trigger unit 82. When the first trigger unit 81 is in state one, the control logic circuit 7 works according to a preset timing. When the first trigger unit 81 is in state two, the control logic circuit 7 detects that the second trigger unit 82 is in a specific state and performs a round of Tuner state polling and adjustment.

[0031] The external main control unit controls the control logic circuit 7 through two signal lines, the first trigger unit 81 and the second trigger unit 82. When the first trigger unit 81 is in state 1, the internal control logic circuit 7 works according to the preset timing; when the first trigger unit 81 is in state 2, the second trigger unit 82 takes effect. At this time, the internal control logic circuit 7 will only perform a round of polling and tuner adjustment when it detects that the second trigger unit 82 is in a specific state.

[0032] In this embodiment, the adaptive impedance adjustment circuit 100 further includes an interstage matching circuit, the input end of the interstage matching circuit is connected to the output end of the power amplifier, and the output end of the interstage matching circuit is connected to the input end of the impedance tuning circuit 2. The interstage matching circuit is used to match the signal output by the power amplifier, so that the impedance tuning circuit 2 receives the matching signal output by the interstage matching circuit to perform impedance tuning with good effect.

[0033] Optionally, the inter-stage matching circuit generally includes a capacitor and a resistor, which are arranged in series or in parallel and connected to the output end of the power amplifier to improve circuit efficiency and avoid nonlinear distortion, with high safety.

[0034] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. An adaptive impedance adjustment circuit, comprising a power amplifier, a directional coupler and a control logic circuit connected in sequence, characterized in that: The adaptive impedance adjustment circuit also includes an impedance tuning circuit, a first power detector and a second power detector. The output end of the power amplifier is connected to the input end of the impedance tuning circuit, the output end of the impedance tuning circuit is connected to the input end of the directional coupler, the output end of the directional coupler is used to connect to a load, the input end of the first power detector is connected to the output end of the power amplifier, the input end of the second power detector is connected to the output end of the directional coupler, the output end of the first power detector and the output end of the second power detector are respectively connected to the input end of the control logic circuit, and the output end of the control logic circuit is connected to the input end of the impedance tuning circuit; the first power detector and the second power detector respectively detect the output signal of the power amplifier and the reverse signal reflected from the load to the directional coupler, and respectively convert the output signal and the reverse signal into a first DC voltage and a second DC voltage; the control logic circuit receives the first DC voltage and the second DC voltage respectively, and outputs a control signal to the impedance tuning circuit after common processing to achieve adaptive adjustment; The control logic circuit receives the first DC voltage and the second DC voltage, and calculates the reflection coefficient of the control signal; wherein the first DC voltage is defined as Vdet1, the second DC voltage is defined as Vdet2, and the reflection coefficient is defined as R, R=Vdet2 / Vdet1; The reflection coefficient includes multiple and is R(n-1); the impedance tuning circuit includes multiple Tuner states and is Tu(n-1); wherein the multiple reflection coefficients correspond one-to-one to the multiple Tuner states, and n represents the number.

2. The adaptive impedance adjustment circuit according to claim 1, characterized in that: The adaptive impedance adjustment circuit also includes an external main control circuit, the output end of the external main control circuit is connected to the input end of the control logic circuit, and the output end of the control logic circuit outputs the control signal to the impedance tuning circuit.

3. The adaptive impedance adjustment circuit according to claim 2, characterized in that: The external main control circuit includes a first trigger unit and a second trigger unit. When the first trigger unit is placed in state one, the control logic circuit operates according to a preset timing. When the first trigger unit is placed in state two and the control logic circuit detects that the second trigger unit is placed in a specific state, a round of Tuner state polling and adjustment is performed.

4. The adaptive impedance adjustment circuit according to claim 1, wherein: The adaptive impedance adjustment circuit also includes an inter-stage matching circuit, the input end of the inter-stage matching circuit is connected to the output end of the power amplifier, and the output end of the inter-stage matching circuit is connected to the input end of the impedance tuning circuit.

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