An automatic control circuit for the power supply voltage of a transmitter current source changing with load

Abstract

The present invention relates to an automatic control circuit for a transmitter current source whose power supply voltage changes with load, which comprises a current source output circuit, a voltage follower circuit, a load voltage sampling differential processing circuit and a current source power supply voltage circuit, wherein the current source output circuit is connected to the voltage follower circuit, the voltage follower circuit is connected to the load voltage sampling differential processing circuit, the load voltage sampling differential processing circuit is connected to the current source power supply voltage circuit, and the current source power supply voltage circuit is connected to the current source output circuit. The present invention realizes automatic control of the current source output voltage as the load size changes, ensures that there is no waste of extra power consumption when the load is met, and the current source output accuracy and temperature drift are minimally affected, thereby ensuring the performance of the transmitter product.

Description

Technical Field

[0001] The invention relates to the technical field of control circuits, and in particular to an automatic control circuit in which the power supply voltage of a transmitter current source varies with load. Background Art

[0002] The output load capacity of the transmitter current source output needs to be considered, so the current source output needs to be designed with a higher power supply voltage. If the current source power supply voltage is designed to be a fixed value, the downstream load in the field application is small, and the MOS tube inside the transmitter shares a higher voltage, the MOS tube power will increase and the heat generated will increase. On the one hand, additional power consumption is generated, which is a waste of energy. On the other hand, the heat generated will affect the output accuracy and temperature drift of the current source.

[0003] Therefore, there is an urgent need for a circuit that can automatically control the power supply voltage of a transmitter current source as the load changes. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a circuit for automatically regulating the power supply voltage of a transmitter current source as the load changes, so as to realize automatic regulation of the output voltage of the current source as the load changes.

[0005] The object of the present invention is achieved in that:

[0006] A circuit for automatically regulating the power supply voltage of a transmitter current source as the power supply voltage changes with the load, comprising a current source output circuit, a voltage following circuit, a load voltage sampling differential processing circuit and a current source power supply voltage circuit, wherein the current source output circuit is connected to the voltage following circuit, the voltage following circuit is connected to the load voltage sampling differential processing circuit, the load voltage sampling differential processing circuit is connected to the current source power supply voltage circuit, and the current source power supply voltage circuit is connected to the current source output circuit;

[0007] The current source output circuit includes an operational amplifier U2B, a driving resistor R12, a MOS tube Q2 and a sampling resistor R13 to realize the conversion from voltage to current. The current source circuit formed by the operational amplifier U2B satisfies negative feedback, and the output current size Iout is controlled by the voltage Vin of pin 5 of the operational amplifier U2B; the load voltage sampling differential processing circuit 3 includes a voltage processing circuit and a differential amplifier circuit; the voltage processing circuit includes an operational amplifier U1A, an operational amplifier U1B and an operational amplifier U1D, and the operational amplifier U1D performs voltage following on the upper end voltage V1 of the load RL; the operational amplifier U1B performs voltage following on the lower end voltage V2 of the load RL ; The differential amplifier circuit includes an operational amplifier U1A, a resistor R6, a resistor R8, a resistor R10 and a resistor R11, which are used for differential amplification; the resistors R7, R9, R5 and the transistor Q1 form an effect in which a voltage V4 changes inversely with a voltage V3, that is, when the voltage V3 increases, the voltage V4 decreases; when the voltage V3 decreases, the voltage V4 increases; the voltage follower circuit includes an operational amplifier U1C, which is used for following the voltage V4, and the output voltage Vout is regulated by controlling the pin FB of the step-down chip IC1 through the resistor R4, that is, when the voltage V4 increases, the output voltage Vout decreases; when the voltage V4 decreases, the output voltage Vout increases.

[0008] A circuit for automatically regulating the power supply voltage of a transmitter current source as the load changes. The voltages at the same-direction input terminal at pin 5 and the reverse input terminal at pin 6 of the operational amplifier U2B are approximately equal, that is, the voltage of the sampling resistor R13 is approximately equal to the voltage at pin 5 of the operational amplifier U2B. Therefore, when the sampling resistor R13 is determined, the output current Iout is controlled by the voltage Vin at pin 5 of the operational amplifier U2B.

[0009] A circuit for automatically regulating the power supply voltage of a transmitter current source as the load changes. Appropriate resistance parameters are selected in the differential amplifier circuit to achieve an output result of the operational amplifier U1A of V3=V1-V2, which is the load voltage.

[0010] Compared with the prior art, the present invention has the following beneficial effects:

[0011] The present invention provides an automatic control circuit for a transmitter current source whose power supply voltage changes with the load. When the load becomes smaller, the power supply voltage becomes smaller with the load, and when the load becomes larger, the power supply voltage becomes larger with the load, ensuring that there is no waste of extra power consumption under the load condition, and the output accuracy and temperature drift of the current source are minimally affected, thereby ensuring the performance of the transmitter product. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a structural schematic diagram of the present invention.

[0013] Figure 2 Schematic diagram of the circuit of the present invention.

[0014] Figure 3 This is a block diagram of the regulation changes when the load RL increases according to the present invention.

[0015] Figure 4 This is a block diagram of the regulation changes when the load RL becomes smaller in the present invention.

[0016] in:

[0017] Current source output circuit 1, voltage follower circuit 2, load voltage sampling differential processing circuit 3, current source power supply voltage circuit 4. DETAILED DESCRIPTION

[0018] In order to better understand the technical solution of the present invention, the following will be described in detail in conjunction with the relevant illustrations. It should be understood that the following specific embodiments are not intended to limit the specific implementation of the technical solution of the present invention, and are only implementations that can be adopted by the technical solution of the present invention. It should be noted that the description of the positional relationship of each component in this article, such as component A being located above component B, is based on the description of the relative positions of the components in the illustration, and is not intended to limit the actual positional relationship of the components.

[0019] Embodiment 1:

[0020] See also Figure 1-4 , Figure 1 The structural schematic diagram of the present invention is drawn. As shown in the figure, the present invention relates to an automatic control circuit of a transmitter current source whose power supply voltage changes with the load, which includes a current source output circuit 1, a voltage follower circuit 2, a load voltage sampling differential processing circuit 3 and a current source power supply voltage circuit 4, the current source output circuit 1 is connected to the voltage follower circuit 2, the voltage follower circuit 2 is connected to the load voltage sampling differential processing circuit 3, the load voltage sampling differential processing circuit 3 is connected to the current source power supply voltage circuit 4, and the current source power supply voltage circuit 4 is connected to the current source output circuit 1.

[0021] The current source output circuit 1 includes an operational amplifier U2B, a driving resistor R12, a MOS tube Q2 and a sampling resistor R13 to realize voltage-to-current conversion. The current source circuit formed by the operational amplifier U2B satisfies negative feedback, and the voltages at the same-direction input terminal of pin 5 and the reverse input terminal of pin 6 of the operational amplifier U2B are approximately equal, that is, the voltage of the sampling resistor R13 is approximately equal to the voltage of pin 5 of the operational amplifier U2B. Therefore, when the sampling resistor R13 is determined, the output current size Iout is controlled by the voltage Vin of pin 5 of the operational amplifier U2B.

[0022] The load voltage sampling differential processing circuit 3 includes a voltage processing circuit and a differential amplifier circuit; the voltage processing circuit includes an operational amplifier U1A, an operational amplifier U1B and an operational amplifier U1D, the operational amplifier U1D performs voltage following on the upper end voltage V1 of the load RL; the operational amplifier U1B performs voltage following on the lower end voltage V2 of the load RL;

[0023] The differential amplifier circuit includes an operational amplifier U1A, a resistor R6, a resistor R8, a resistor R10 and a resistor R11, which are used for differential amplification. Appropriate resistance parameters are selected to achieve an output result of the operational amplifier U1A of V3=V1-V2, that is, the load voltage.

[0024] The resistors R7, R9, R5 and transistor Q1 form a voltage V4 that has the opposite effect of changing with the voltage V3, that is, as the voltage V3 increases, the voltage V4 decreases; as the voltage V3 decreases, the voltage V4 increases.

[0025] The voltage follower circuit 2 includes an operational amplifier U1C, which is used for following the voltage V4. The resistor R4 controls the pin FB of the buck chip IC1, thereby regulating the output voltage Vout, that is, when the voltage V4 increases, the output voltage Vout decreases; when the voltage V4 decreases, the output voltage Vout increases.

[0026] Working principle:

[0027] The present invention provides a transmitter current source power supply voltage automatic regulation circuit as the load changes. An operational amplifier U2B, a driving resistor R12, a MOS tube Q2, and a sampling resistor R13 constitute a current source circuit to realize voltage-to-current conversion; operational amplifiers U1D, U1B, and U1A constitute a voltage processing circuit of a load RL; a transistor Q1, resistors R9, and R5 constitute a voltage change trend inversion circuit; an operational amplifier U1C acts as a voltage follower circuit, and controls an FB pin of a step-down power supply chip IC1 through a resistor R4 to regulate the output voltage Vout of the power supply chip IC1. As the load increases, the current source voltage Vout also increases accordingly; as the load decreases, the current source voltage Vout decreases accordingly, thereby realizing automatic regulation of the current source output voltage as the load changes.

[0028] The above are only specific application examples of the present invention and do not constitute any limitation on the protection scope of the present invention. Any technical solution formed by equivalent transformation or equivalent replacement shall fall within the protection scope of the present invention.

Claims

1. An automatic control circuit for a current source of a transmitter in which the power supply voltage varies with load, characterized in that: It includes a current source output circuit, a voltage follower circuit, a load voltage sampling differential processing circuit and a current source power supply voltage circuit, the current source output circuit is connected to the voltage follower circuit, the voltage follower circuit is connected to the load voltage sampling differential processing circuit, the load voltage sampling differential processing circuit is connected to the current source power supply voltage circuit, and the current source power supply voltage circuit is connected to the current source output circuit; The current source output circuit includes an operational amplifier U2B, a driving resistor R12, a MOS tube Q2 and a sampling resistor R13 to realize the conversion from voltage to current. The current source circuit formed by the operational amplifier U2B satisfies negative feedback, and the output current size Iout is controlled by the voltage Vin of pin 5 of the operational amplifier U2B; the load voltage sampling differential processing circuit includes a voltage processing circuit and a differential amplifier circuit; the voltage processing circuit includes an operational amplifier U1A, an operational amplifier U1B and an operational amplifier U1D, and the operational amplifier U1D performs voltage following on the upper end voltage V1 of the load RL; the operational amplifier U1B performs voltage following on the lower end voltage V2 of the load RL ; The differential amplifier circuit includes an operational amplifier U1A, a resistor R6, a resistor R8, a resistor R10 and a resistor R11, which are used for differential amplification; the resistors R7, R9, R5 and the transistor Q1 form an effect in which a voltage V4 changes inversely with a voltage V3, that is, when the voltage V3 increases, the voltage V4 decreases; when the voltage V3 decreases, the voltage V4 increases; the voltage follower circuit includes an operational amplifier U1C, which is used for following the voltage V4, and controls the pin FB of the step-down chip IC1 through the resistor R4, thereby regulating the output voltage Vout, that is, when the voltage V4 increases, the output voltage Vout decreases; when the voltage V4 decreases, the output voltage Vout increases; The voltages at the non-inverting input terminal of pin 5 and the reverse input terminal of pin 6 of the operational amplifier U2B are approximately equal, that is, the voltage of the sampling resistor R13 is approximately equal to the voltage at pin 5 of the operational amplifier U2B. Therefore, when the sampling resistor R13 is determined, the output current Iout is controlled by the voltage Vin at pin 5 of the operational amplifier U2B. Appropriate resistance parameters are selected in the differential amplifier circuit to achieve an output result of the operational amplifier U1A of V3=V1-V2, which is the load voltage.

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