阅读说明：本技术 一种控制功率放大器输出功率的控制电路 (Control circuit for controlling output power of power amplifier ) 是由 奉靖皓 倪建兴 于 2020-04-23 设计创作，主要内容包括：本发明公开了一种控制功率放大器输出功率的控制电路,该控制电路包括：偏置电路,根据输入的控制电压生成偏置电流,所述偏置电流耦合至功率放大器的输入端；输出电压控制电路,根据输入的所述控制电压调整输出电压,所述输出电压耦合至功率放大器的输出端。本发明提供的控制电路利用偏置电路将电压转换电流的方式控制功率放大器的输出功率,达到了功率放大器的输出功率由控制电压控制的目的,避免了使用昂贵的片外精准电阻,节省了成本。(The invention discloses a control circuit for controlling the output power of a power amplifier, which comprises: the bias circuit generates a bias current according to an input control voltage, and the bias current is coupled to the input end of the power amplifier; and the output voltage control circuit adjusts output voltage according to the input control voltage, and the output voltage is coupled to the output end of the power amplifier. The control circuit provided by the invention controls the output power of the power amplifier by converting the voltage into the current by using the bias circuit, achieves the purpose that the output power of the power amplifier is controlled by the control voltage, avoids using expensive off-chip precise resistor and saves the cost.)

1. A control circuit for controlling the output power of a power amplifier, comprising:

the bias circuit generates a bias current according to an input control voltage, and the bias current is coupled to the input end of the power amplifier;

and the output voltage control circuit adjusts output voltage according to the input control voltage, and the output voltage is coupled to the output end of the power amplifier.

2. The control circuit of claim 1 for controlling the output power of a power amplifier, wherein: the bias circuit includes a voltage controlled current source that generates a bias current that is exponentially related to the control voltage, the bias current being coupled to an input of a power amplifier.

3. The control circuit of claim 2, wherein: the voltage-controlled current source comprises an operational amplifier M1, a field-effect transistor Q1, a field-effect transistor Q2 and a field-effect transistor Q3, the control voltage is loaded at the reverse input end of the operational amplifier M1, the forward input end of the operational amplifier M1 is connected with the drain electrodes of the field-effect transistor Q1 and the field-effect transistor Q2, and the grid electrode of the field-effect transistor Q2 is connected with the grid electrode of the field-effect transistor Q3 and the drain electrode of the field-effect transistor Q2; the drain of the field effect transistor Q3 is used as an output terminal to output a bias current.

4. A control circuit for controlling the output power of a power amplifier as claimed in claim 1, 2 or 3, characterized in that: the output voltage control circuit comprises a control voltage detection module and a power supply module, wherein the control voltage detection module detects the control voltage and outputs a comparison voltage;

the power supply module outputs an output voltage to an output end of the power amplifier according to the comparison voltage, wherein the output voltage is positively correlated with the comparison voltage.

5. The circuit of claim 4, wherein the power supply module is an L DO module or a DCDC module.

6. The control circuit of claim 4 for controlling the output power of a power amplifier, wherein: the power supply module comprises a comparator M2, a field-effect transistor Q4 and a field-effect transistor Q5, the comparison voltage output by the control voltage detection module is loaded at the non-inverting input end of the comparator M2, the inverting input end of the comparator M2 is grounded through a resistor R1, and the output end of the comparator M2 is connected with the gates of the field-effect transistor Q4 and the field-effect transistor Q5; the field effect transistor Q4 is grounded through the resistor R1, the source electrode of the field effect transistor Q5 is grounded, and the drain electrode of the field effect transistor Q5 is used as an output end to be connected with the output end of the power amplifier.

7. The circuit of claim 4 further comprising an L C circuit, wherein the output voltage of the power supply module is coupled to the output of the power amplifier via the L C circuit.

Technical Field

The invention relates to a control circuit for controlling the output power of a power amplifier.

Background

The power amplifier is a device capable of amplifying the voltage or power of an input signal and consists of an electronic tube or a transistor, a power transformer and other electrical elements; is widely used in various devices such as communication, broadcasting, radar, television, automatic control and the like.

The output power of the power amplifier needs to be controlled within a certain range. Taking the cellular data rf front end of a mobile phone as an example, the power amplifier system currently needs to output power as high as 33 dBm. The battery needs to provide ampere-level current for the power amplifier, and if the output power of the power amplifier is improperly controlled, serious heat dissipation problems are easily caused.

Disclosure of Invention

In order to solve the problems in the prior art, an object of the present invention is to provide a control circuit for controlling the output power of a power amplifier, which can effectively control the output power of the power amplifier and save the cost.

To achieve the object of the present invention, there is provided a control circuit for controlling output power of a power amplifier, comprising:

the bias circuit generates a bias current according to an input control voltage, and the bias current is coupled to the input end of the power amplifier;

and the output voltage control circuit adjusts output voltage according to the input control voltage, and the output voltage is coupled to the output end of the power amplifier.

Further, the bias circuit includes a voltage controlled current source that generates a bias current that is exponential to the control voltage, the bias current being coupled to an input of the power amplifier.

Further, the voltage-controlled current source comprises an operational amplifier M1, a field-effect transistor Q1, a field-effect transistor Q2 and a field-effect transistor Q3, the control voltage is applied to the inverting input terminal of the operational amplifier M1, the forward input terminal of the operational amplifier M1 is connected with the drains of the field-effect transistor Q1 and the field-effect transistor Q2, and the gate of the field-effect transistor Q2 is connected with the gate of the field-effect transistor Q3 and the drain of the field-effect transistor Q2; the drain of the field effect transistor Q3 is used as an output terminal to output a bias current.

Further, the output voltage control circuit comprises a control voltage detection module and a power supply module; the control voltage detection module detects the control voltage and outputs a comparison voltage; the power supply module outputs an output voltage to an output end of the power amplifier according to the comparison voltage, wherein the output voltage is positively correlated with the comparison voltage.

Further, the power supply module is an L DO module or a DCDC module.

Further, the power supply module comprises a comparator M2, a field effect transistor Q4 and a field effect transistor Q5, the comparison voltage output by the control voltage detection module is loaded at the non-inverting input end of the comparator M2, the inverting input end of the comparator M2 is grounded through a resistor R1, and the output end of the comparator M2 is connected with the gates of the field effect transistor Q4 and the field effect transistor Q5; the field effect transistor Q4 is grounded through the resistor R1, the source electrode of the field effect transistor Q5 is grounded, and the drain electrode of the field effect transistor Q5 is used as an output end to be connected with the output end of the power amplifier.

Further, the power supply device also comprises an L C circuit, and the output voltage of the power supply module is coupled to the output end of the power amplifier through the L C circuit.

The beneficial effects of the invention include:

1) the control circuit provided by the invention controls the output power of the power amplifier by converting the voltage into the current by using the bias circuit, achieves the purpose that the output power of the power amplifier is controlled by the control voltage, avoids using expensive off-chip precise resistor and saves the cost.

2) The output voltage control circuit is utilized to control the output voltage under different power modes, thereby achieving the purpose of reducing or improving the output power of the power amplifier.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort. In the drawings:

FIG. 1 is a circuit diagram of a control circuit provided in the present invention;

FIG. 2 is a circuit diagram of a voltage controlled current source according to the present invention;

FIG. 3 is a circuit diagram of a power supply module provided in the present invention;

in the drawings: the device comprises a bias circuit 1, a control voltage detection module 2 and a power supply module 3.

Detailed Description

Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art.

In order to realize the control of the output power of the power amplifier, the circuit structure of the control circuit for controlling the output power of the power amplifier provided herein is shown in fig. 1, and comprises a bias circuit 1, which generates a bias current according to an input control voltage, wherein the bias current is coupled to an input end of the power amplifier; and the output voltage control circuit adjusts the output voltage according to the input control voltage, and the output voltage is coupled to the output end of the power amplifier.

The control circuit converts the control voltage into bias current through a bias circuit 1, and the bias current controls the output power of the power amplifier; the output voltage of the power amplifier is controlled by the output voltage control circuit, and the output voltage also realizes the control of the output power of the power amplifier.

Herein, the bias circuit 1 comprises a voltage controlled current source generating a bias current in exponential relation to a control voltage, the bias current being coupled to the input of the power amplifier. The circuit structure of the voltage-controlled current source is shown in fig. 2, and comprises an operational amplifier M1, a field-effect transistor Q1, a field-effect transistor Q2 and a field-effect transistor Q3, wherein control voltage is loaded at the reverse input end of the operational amplifier M1, the forward input end of the operational amplifier M1 is connected with the drain electrodes of the field-effect transistor Q1 and the field-effect transistor Q2, and the gate electrode of the field-effect transistor Q2 is connected with the gate electrode of the field-effect transistor Q3 and the drain electrode of the field-effect transistor Q2; the drain of the field effect transistor Q3 outputs a bias current as an output terminal.

Herein, the output voltage control circuit includes a control voltage detection module 2 and a power supply module 3; the control voltage detection module 2 detects the control voltage and outputs a comparison voltage; the power supply module 3 outputs an output voltage to the output end of the power amplifier according to the comparison voltage output by the control voltage detection module 2, wherein the output voltage and the comparison voltage are in positive correlation. The control voltage detection module 2 compares the control voltage with a reference voltage, and when the control voltage is greater than the reference voltage, the control voltage detection module 2 outputs a larger comparison voltage to control the power supply module 3 to increase the output voltage, so that the purpose of providing the output power of the power amplifier is achieved; when the control voltage is smaller than the reference voltage, the control voltage detection module 2 outputs a smaller comparison voltage to control the power supply module 3 to reduce the output voltage, so as to achieve the purpose of reducing the output power of the power amplifier.

Here, the power supply module 3 is an L DO module or a DCDC module, as shown in fig. 3, the L DO module is adopted as the power supply module, the L DO module includes a comparator M2, a field-effect transistor Q4 and a field-effect transistor Q5, the comparison voltage output by the control voltage detection module is loaded on the non-inverting input terminal of the comparator M2, the inverting input terminal of the comparator M2 is grounded through a resistor R2, the output terminal of the comparator M2 is connected to the gates of the field-effect transistor Q4 and the field-effect transistor Q5, the source of the field-effect transistor Q4 is grounded through a resistor R1, the source of the field-effect transistor Q5 is directly grounded, the drain of the field-effect transistor Q4 and the source of the field-effect transistor Q5 are connected to a power source VCC, the drain of the field-effect transistor Q5 is connected as the output terminal of the power amplifier, the control voltage detection module 2 compares the control voltage with the reference voltage, and when the control voltage detection module 2.

For better matching, the output voltage of the power supply module 3 is coupled to the output of the power amplifier via the L C circuit.

The control principle of the control circuit provided by the invention is as follows: power = voltage x current, so controlling the output voltage or current of the power amplifier can control the output power.

The control circuit provided herein controls the output power of the power amplifier by controlling the output voltage and the output current of an output stage transistor T1 of the power amplifier, and in conjunction with fig. 1, PA represents the power amplifier, TI represents the output stage transistor of the power amplifier, and the output stage transistor of the power amplifier refers to the stage of the power amplifier where the current and the power are the largest.

Referring to fig. 1, the bias current output by the bias circuit 1 is applied to the base of the output stage transistor T1 of the power amplifier, and since the collector current is proportional to the base current, when the control voltage input to the bias circuit 1 changes, the output bias current changes accordingly, so as to achieve the purpose of controlling the output power by means of the bias current. The output voltage of the output voltage control circuit is coupled to the collector of the output stage transistor T1 of the power amplifier, and the output voltage of the output voltage control circuit is adjusted according to the input control voltage, so as to achieve the purpose of controlling the output power by a voltage mode.

The bias circuit 1, the control voltage detection module 2 and the power supply module 3 are integrated on a CMOS or SOI chip, so that on-chip control is realized; the control voltage is herein provided by an external circuit.

The control circuit provided by the invention is mainly used for controlling power by changing base current, the output voltage of the output voltage control circuit is changed into an auxiliary means, and low power consumption (low-voltage section) or high power (high-voltage section) is realized mainly aiming at a low-voltage section and a high-voltage section of control voltage.

The present disclosure has been described in terms of the above-described embodiments, which are merely exemplary of the implementations of the present disclosure. It must be noted that the disclosed embodiments do not limit the scope of the disclosure. Rather, variations and modifications are possible within the spirit and scope of the disclosure, and these are all within the scope of the disclosure.