Operational amplifier circuit and switching circuit

Abstract

The application discloses an operational amplifier circuit and a switching circuit, comprising a first current type operational amplifier, a first compensation capacitor and a proportional amplification circuit, wherein the first current type operational amplifier receives a first feedback voltage and a reference voltage, the proportional amplification circuit receives a first voltage and a reference voltage and is connected to a common mode voltage, the first voltage and the reference voltage are proportionally amplified, the output of the first current type operational amplifier is connected to the output of the proportional amplification circuit through the first compensation capacitor, and the output of the first current type operational amplifier generates a compensation voltage.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, specifically to an operational amplifier circuit and a switching circuit. Background Technology

[0002] Operational amplifier circuits are widely used in various circuit systems, especially in switching circuits. Speed ​​and offset voltage are two important characteristics of operational amplifier circuits, but it is difficult to achieve both simultaneously. In traditional operational amplifier circuits, reducing the size of the input transistor pair increases speed but increases offset voltage; conversely, increasing the size of the input transistor pair reduces offset voltage but decreases speed. In applications requiring high speed and low offset voltage, optimization is difficult to achieve. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide an operational amplifier circuit and a switching circuit to solve the problem that it is difficult to simultaneously optimize the speed and offset voltage of the operational amplifier circuit in the prior art.

[0004] The technical solution of this invention is to provide a control method for a switching circuit, which generates a first reference voltage, controls the slope of the rising and falling edges to generate a second reference voltage, and performs operational amplification on the output feedback voltage and the reference voltage to obtain a compensation voltage. When the first reference voltage has a falling edge, the reference voltage is connected to the first reference voltage through a first switch, and the second reference voltage is connected to the output voltage through a second switch. When the first reference voltage has a rising edge, the reference voltage is connected to the second reference voltage through a third switch.

[0005] Optionally, the slopes of the rising and falling edges of the first reference voltage can be controlled according to a set slope to generate a second reference voltage.

[0006] Optionally, the central processing unit sets the slope.

[0007] Another technical solution of the present invention is to provide a control circuit for a switching circuit, the control circuit including a slope buffer and a first operational amplifier, the slope buffer receiving a first reference voltage and controlling the slope of the rising edge and falling edge to generate a second reference voltage; the first operational amplifier receiving an output feedback voltage and a reference voltage, performing operational amplification to obtain a compensation voltage;

[0008] When the first reference voltage has a falling edge, the reference voltage is connected to the first reference voltage through a first switch, and the second reference voltage is connected to the output voltage through a second switch; when the first reference voltage has a rising edge, the reference voltage is connected to the second reference voltage through a third switch.

[0009] Optionally, the slopes of the rising and falling edges of the first reference voltage can be controlled according to a set slope to generate a second reference voltage.

[0010] Optionally, the central processing unit sets the slope.

[0011] Optionally, the control circuit may further include a digital-to-analog converter circuit that generates the first reference voltage.

[0012] Optionally, when the first reference voltage has a falling edge, the first signal changes from invalid to valid; when the first reference voltage has a rising edge, the first signal changes from valid to invalid; when the first signal is valid, the reference voltage is connected to the first reference voltage through a first switch, and the second reference voltage is connected to the output voltage through a second switch; when the first signal is invalid, the reference voltage is connected to the second reference voltage through a third switch.

[0013] Optionally, when the first enable signal is valid, the first signal changes from invalid to valid when the first reference voltage has a falling edge; and the first signal changes from valid to invalid when the first reference voltage has a rising edge.

[0014] When the first enable signal is invalid, the first signal is invalid.

[0015] Optionally, the first enable signal is SetVID_Decay.

[0016] Optionally, the slope buffer includes a second operational amplifier and a first capacitor; the first terminal of the second operational amplifier receives a first reference voltage, the second terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier, and is connected to the negative voltage terminal of the output of the switching circuit through the first capacitor.

[0017] Optionally, the first operational amplifier includes a first current-mode operational amplifier, a first compensation capacitor, a proportional amplifier circuit, and a first voltage follower. The first current-mode operational amplifier receives an output feedback voltage and a reference voltage. The proportional amplifier circuit receives an output voltage and a reference voltage and is connected to a common-mode voltage. The output of the first current-mode operational amplifier is connected to the output of the proportional amplifier circuit through the first compensation capacitor. The output of the first current-mode operational amplifier generates a compensation voltage through the first voltage follower.

[0018] Another technical solution of the present invention is to provide an operational amplifier circuit, including a first current-type operational amplifier, a first compensation capacitor, and a proportional amplifier circuit. The first current-type operational amplifier receives a first feedback voltage and a reference voltage. The proportional amplifier circuit receives the first voltage and the reference voltage and is connected to a common-mode voltage to proportionally amplify the first voltage and the reference voltage. The output of the first current-type operational amplifier is connected to the output of the proportional amplifier circuit through the first compensation capacitor, and the output of the first current-type operational amplifier generates a compensation voltage.

[0019] Optionally, the proportional amplifier circuit includes a second current-mode operational amplifier and a first resistor. The second current-mode operational amplifier receives a first voltage and a reference voltage. The output of the second current-mode operational amplifier is connected to a common-mode voltage through the first resistor. The output of the second current-mode operational amplifier is the output of the proportional amplifier circuit.

[0020] Optionally, a first voltage follower is also included, wherein the output of the first current-type operational amplifier generates a compensation voltage through the first voltage follower.

[0021] Optionally, the gain of the second current-type operational amplifier is k times that of the first current-type operational amplifier, where k is greater than 1.

[0022] Optionally, the first voltage is the output voltage, the first feedback voltage is the output feedback voltage, the output voltage is connected to the output feedback voltage through the second resistor, and the output sampling current is connected to the output feedback voltage.

[0023] Optionally, the first voltage is connected to the first feedback voltage via a voltage divider circuit; the voltage divider circuit divides the first voltage.

[0024] Optionally, the voltage divider circuit includes a first control switch, a second control switch, a voltage divider resistor, and a second voltage follower. The first voltage is connected to the input terminal of the second voltage follower via the first control switch, and the first voltage is connected to the second control switch via the voltage divider resistor. The second control switch is connected to the input terminal of the second voltage follower, and the output terminal of the second voltage follower is connected to the first feedback voltage. The operational amplifier circuit receives the reference voltage and the input voltage of the second voltage follower.

[0025] Another technical solution of the present invention is to provide a switching circuit.

[0026] Compared with the prior art, the circuit structure and method of the present invention have the following advantages: the speed of the operational amplifier circuit and the offset voltage can be optimized simultaneously. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the control circuit of the present invention;

[0028] Figure 2 This is a waveform diagram of the first signal, first reference voltage, second reference voltage, and reference voltage of the control circuit of the present invention;

[0029] Figure 3 This is a circuit diagram of one embodiment of the digital-to-analog converter circuit 100 of the control circuit of the present invention;

[0030] Figure 4 This is a circuit diagram of one embodiment of the operational amplifier 300 of the present invention;

[0031] Figure 5 This is a circuit diagram of another embodiment of the operational amplifier 300 of the present invention;

[0032] Figure 6 A circuit diagram of one embodiment of the operational amplifier 300 of the present invention with a DROOP added;

[0033] Figure 7 A circuit diagram of one embodiment of the operational amplifier 300 of the present invention with a voltage divider circuit added;

[0034] Figure 8 This is a circuit diagram of one embodiment of the operational amplifier 300 of the present invention with the addition of a DROOP and a voltage divider circuit. Detailed Implementation

[0035] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings, but the present invention is not limited to these embodiments. The present invention covers any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of the present invention.

[0036] To provide the public with a thorough understanding of the present invention, specific details are described in detail in the following preferred embodiments of the invention, but those skilled in the art can fully understand the invention without these details.

[0037] The invention is described in more detail below by way of example with reference to the accompanying drawings. It should be noted that the drawings are in a simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the invention.

[0038] This invention provides a control circuit for a switching circuit; please refer to [the relevant documentation]. Figure 1As shown, the control circuit includes a slope buffer 200 and a first operational amplifier 300. The slope buffer 200 receives a first reference voltage VA and controls the slope of the rising and falling edges to generate a second reference voltage VB. The first operational amplifier 300 receives an output feedback voltage VFB and a reference voltage VBR, performs operational amplification, and obtains a compensation voltage COMP. When a falling edge occurs in the first reference voltage VA, the reference voltage VBR is connected to the first reference voltage VA through a first switch K410, and the second reference voltage VB is connected to the output voltage VO+ through a second switch K420. When a rising edge occurs in the first reference voltage VA, the reference voltage VBR is connected to the second reference voltage VB through a third switch K430. Please refer to [reference needed]. Figure 2 The diagram shows the waveforms of the first reference voltage VA, the second reference voltage VB, and the reference voltage VBR in the control circuit of this invention. At time t01, the first reference voltage VA experiences a falling edge. After passing through the slope buffer 200, the falling edge slope of the second reference voltage VB becomes gentler, and the reference voltage VBR is at the same voltage as the first reference voltage VA at this time. At time t02, the first reference voltage VA experiences a rising edge. At this time, the second reference voltage VB has not yet dropped to the voltage of the first reference voltage VA between times t01 and t02, and begins to rise slowly. The reference voltage VBR jumps to the value of the second reference voltage VB and begins to rise slowly like the second reference voltage VB. This invention uses analog circuits to realize the reference voltage following the output voltage, which is convenient and low-cost.

[0039] In one embodiment, the slopes of the rising and falling edges of the first reference voltage VA are controlled according to a set slope. The set slope is not limited to... Figure 2 The slope in the equation is linear and can be any slope. In one embodiment, the central processing unit (CPU) sets the slope.

[0040] Please continue to refer to this. Figure 1 As shown, the control circuit also includes a digital-to-analog converter circuit 100, which generates the first reference voltage VA.

[0041] Please refer to Figure 3The diagram illustrates one embodiment of a digital-to-analog converter (DAC) circuit 100. The DAC circuit 100 includes an operational amplifier (op-amp) 110, a current mirror composed of switching transistors M120 and M130, a switching transistor M110, resistors R110 and R120. The op-amp 110 receives an internal reference voltage VBG and the voltage across resistor R110. The output of the op-amp 110 is connected to the gate of the switching transistor M110. The source of the switching transistor M110 is connected to resistor R110, the other end of resistor R110 is connected to reference ground, and the drain of the switching transistor M110 is connected to the input of the current mirror. A digital signal controls the actual number of current mirrors connected. The output of the current mirror is connected to resistor R120, and the voltage across resistor R120 is the output voltage of the DAC circuit 100.

[0042] In one embodiment, a first signal is used to control a first switch K410, a second switch K420, and a third switch K430. When a falling edge occurs at the first reference voltage VA, the first signal TRACK changes from inactive to active; when a rising edge occurs at the first reference voltage, the first signal TRACK changes from active to inactive. When the first signal is active, the reference voltage VBR is connected to the first reference voltage VA through the first switch K410, and the second reference voltage VB is connected to the output voltage VO+ through the second switch K420. When the first signal TRACK is inactive, the reference voltage is connected to the second reference voltage VB through the third switch K430. Figure 1 TRACKB and TRACK are logically complementary. In one embodiment, a valid TRACKB corresponds to a high level and an invalid TRACKB corresponds to a low level; in another embodiment, a valid TRACKB corresponds to a low level and an invalid TRACKB corresponds to a high level.

[0043] In one embodiment, when the first enable signal is active, the first signal changes from inactive to active when the first reference voltage has a falling edge; when the first reference voltage has a rising edge, the first signal changes from active to inactive; and when the first enable signal is inactive, the first signal is inactive. The first enable signal is SetVID_Decay. SetVID_Decay is an instruction in the SVID protocol used for communication between the Intel processor and its power supply, used to cause the power supply's output voltage to decrease to a new target value at a slope determined by the load, thereby saving power consumption.

[0044] In one embodiment, please refer to... Figure 1 As shown, the slope buffer 200 includes a second operational amplifier 210 and a first capacitor C210; the first terminal of the second operational amplifier 210 receives a first reference voltage VA, the second terminal of the second operational amplifier 210 is connected to the output terminal VB of the second operational amplifier 210, and is connected to the negative voltage terminal VO- of the output of the switching circuit through the first capacitor C210.

[0045] Please refer to Figure 4 As shown, the first operational amplifier 300 includes a first current-mode operational amplifier 310, a first compensation capacitor C310, a proportional amplifier circuit 320, and a first voltage follower 330. The first current-mode operational amplifier 310 receives an output feedback voltage VFB and a reference voltage VBR. The proportional amplifier circuit 320 receives an output voltage VO+ and a reference voltage VBR. The proportional amplifier circuit 320 is connected to a common-mode voltage VDC. The output of the first current-mode operational amplifier 310 is connected to the output of the proportional amplifier circuit 320 through the first compensation capacitor C310. The output of the first current-mode operational amplifier 310 generates a compensation voltage COMP through the first voltage follower 330.

[0046] The technical solution of this invention is to provide a control method for a switching circuit, which generates a first reference voltage, controls the slope of the rising and falling edges to generate a second reference voltage, and performs operational amplification on the output feedback voltage and the reference voltage to obtain a compensation voltage. When the first reference voltage has a falling edge, the reference voltage is connected to the first reference voltage through a first switch, and the second reference voltage is connected to the output voltage through a second switch. When the first reference voltage has a rising edge, the reference voltage is connected to the second reference voltage through a third switch.

[0047] Optionally, the slopes of the rising and falling edges of the first reference voltage can be controlled according to a set slope.

[0048] Optionally, the central processing unit sets the slope.

[0049] Another technical solution of the present invention is to provide an operational amplifier circuit, please refer to... Figure 4 As shown, the circuit includes a first current-mode operational amplifier 310, a first compensation capacitor C310, and a proportional amplifier circuit 320. The first current-mode operational amplifier 310 receives a first feedback voltage VFB and a reference voltage VBR. The proportional amplifier circuit 320 receives the first voltage and the reference voltage VBR and is connected to a common-mode voltage VDC to proportionally amplify the first voltage and the reference voltage VBR. The output of the first current-mode operational amplifier 310 is connected to the output of the proportional amplifier circuit 320 through the first compensation capacitor C310, and the output of the first current-mode operational amplifier 310 generates a compensation voltage COMP. In one embodiment, a first voltage follower 330 is also included, and the output of the first current-mode operational amplifier 310 generates the compensation voltage through the first voltage follower 330. Figure 4 In the circuit, the output of the first current-type operational amplifier 310 is converted into a compensation voltage COMP by a voltage follower 330. The voltage follower 330 prevents the circuit connected after the compensation voltage COMP from affecting the operational amplifier circuit. Therefore, the voltage follower 330 can also be omitted.

[0050] Please refer to Figure 5 As shown, this is one embodiment of a proportional amplifier circuit 320, which includes a second current-type operational amplifier 321 and a first resistor R310. The second current-type operational amplifier 321 receives a first voltage and a reference voltage VBR. The output of the second current-type operational amplifier 321 is connected to the common-mode voltage VDC through the first resistor R310. The output of the second current-type operational amplifier 321 is the output of the proportional amplifier circuit 320.

[0051] In one embodiment, the gain of the second current-type operational amplifier 321 is k times that of the first current-type operational amplifier 310, where k is greater than 1.

[0052] Please refer to Figure 6 As shown, in one embodiment, a DROOP function is added. This means that when the output current is large, the output voltage decreases due to the voltage drop across the output conductors. Since the voltage sampled for output voltage feedback does not include this voltage drop across the conductors, it is necessary to consider it as well. The first voltage is the output voltage VO+, and the first feedback voltage VFB is the output feedback voltage. The output voltage VO+ is connected to the output feedback voltage via a second resistor R340, and the output sampling current Itotal is also connected to the output feedback voltage. By sampling the output current, a voltage drop is generated across the second resistor R340, which is used to represent the equivalent voltage drop across the output conductors.

[0053] Please refer to Figure 7As shown, in one embodiment, an output voltage divider function is added. The first voltage is connected to the first feedback voltage via a voltage divider circuit; the voltage divider circuit divides the first voltage. The voltage divider circuit includes a first control switch K310, a second control switch K320, voltage divider resistors R320 and R330, and a second voltage follower 340. The first voltage is connected to the input terminal of the second voltage follower 340 via the first control switch K310, and the first voltage is connected to the second control switch K320 via the voltage divider resistor R320. The second control switch K320 is connected to the input terminal of the second voltage follower 340, and the output terminal of the second voltage follower 340 is connected to the first feedback voltage VFB. The operational amplifier circuit receives the reference voltage VBR and the input voltage VOS+ of the second voltage follower. When the first control switch K310 is on and the second control switch K320 is off, the first voltage is connected to the first feedback voltage via a voltage follower, and the value of the first feedback voltage is equal to the first voltage. When the second control switch K320 is on and the first control switch K310 is off, the first voltage is divided by a resistor and then connected to the first feedback voltage via a voltage follower, and the value of the first feedback voltage is equal to the voltage value after the first voltage is divided. In the switching circuit, the first voltage is the output voltage, and the first feedback voltage is the output feedback voltage.

[0054] In one embodiment, both output voltage divider and DROOP functions can be added simultaneously. Please refer to [reference needed]. Figure 8 As shown, the output voltage passes through a voltage divider circuit, then through a circuit consisting of resistor R340 and the output sampling current Itotal to implement the DROOP function, and is connected to the feedback voltage VFB.

[0055] Another technical solution of the present invention is to provide a switching circuit.

[0056] Although the embodiments are described and illustrated separately above, some common technologies are involved. Those skilled in the art can replace and integrate them between the embodiments. If there is any content not explicitly described in one embodiment, then another described embodiment can be referred to.

[0057] The embodiments described above do not constitute a limitation on the scope of protection of this technical solution. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the above embodiments should be included within the scope of protection of this technical solution.

Claims

1. An operational amplifier circuit, characterized in that: It includes a first current-mode operational amplifier, a first compensation capacitor, and a proportional amplifier circuit. The first current-mode operational amplifier receives the first feedback voltage and the reference voltage. The proportional amplifier circuit receives a first voltage and a reference voltage, and is connected to a common-mode voltage to proportionally amplify the first voltage and the reference voltage. The output of the first current-source operational amplifier is connected to the output of the proportional amplifier circuit through a first compensation capacitor, and the output of the first current-source operational amplifier generates a compensation voltage. The proportional amplifier circuit includes a second current-mode operational amplifier and a first resistor. The second current-mode operational amplifier receives a first voltage and a reference voltage. The output of the second current-mode operational amplifier is connected to a common-mode voltage through the first resistor. The output of the second current-mode operational amplifier is the output of the proportional amplifier circuit. The first voltage is the output voltage, the first feedback voltage is the output feedback voltage, the output voltage is connected to the output feedback voltage through the second resistor, and the output sampling current is connected to the output feedback voltage. When the first reference voltage has a falling edge, the reference voltage is connected to the first reference voltage through the first switch, and the second reference voltage is connected to the output voltage through the second switch; When the first reference voltage has a rising edge, the reference voltage is connected to the second reference voltage through a third switch. The first reference voltage is generated by a digital-to-analog converter circuit, which controls the slope of the rising and falling edges to generate the second reference voltage.

2. The operational amplifier circuit according to claim 1, characterized in that: It also includes a first voltage follower, the output of the first current-type operational amplifier generates a compensation voltage through the first voltage follower.

3. The operational amplifier circuit according to claim 2, characterized in that: The gain of the second current-type operational amplifier is k times that of the first current-type operational amplifier, where k is greater than 1.

4. The operational amplifier circuit according to claim 1, characterized in that: The first voltage is connected to the first feedback voltage via a voltage divider circuit; the voltage divider circuit divides the first voltage.

5. The operational amplifier circuit according to claim 4, characterized in that: The voltage divider circuit includes a first control switch, a second control switch, a voltage divider resistor, and a second voltage follower. A first voltage is connected to the input terminal of the second voltage follower via the first control switch, and the first voltage is connected to the second control switch via the voltage divider resistor. The second control switch is connected to the input terminal of the second voltage follower, and the output terminal of the second voltage follower is connected to the first feedback voltage. The operational amplifier circuit receives a reference voltage and the input voltage of the second voltage follower.

6. A switching circuit, characterized in that: The first voltage is the output voltage of the switching circuit, and the first feedback voltage is the output feedback voltage, including the operational amplifier circuit as described in any one of claims 1 to 5.

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