An operational amplifier circuit, a method of adjusting the same, and a controller

Abstract

The application provides an operational amplifier circuit, a regulating method and a controller thereof. The operational amplifier circuit comprises a first operational amplifier unit, which performs operational amplification on an input signal to generate a first output signal; and a tail current regulating circuit, which generates a first current according to a reference voltage and generates a tail current of the first operational amplifier unit according to the first current. The tail current of the first operational amplifier unit reaches an expected current by adjusting the size of the first current, and the response time of the first output signal reaches a first preset time when the first input signal or / and the second input signal changes. The application adjusts the response time of the output signal of the operational amplifier circuit by adjusting the size of the tail current, so that the response time reaches the expected time and the response time is not affected by process variation.

Description

Technical Field

[0001] This invention relates to the field of power electronics, and in particular to an operational amplifier circuit, its adjustment method, and a controller. Background Technology

[0002] An operational amplifier is an amplifier with special coupling circuitry and feedback. Its output signal can be the result of mathematical operations such as addition, subtraction, differentiation, or integration of the input signal. Figure 1 This diagram illustrates an operational amplifier such that the output signal Vout can follow the changes in the input signal Vin. When the input signal changes significantly, such as when the input signal is as follows... Figure 2 When a step signal is shown, the limited current in the operational amplifier circuit charges and discharges the capacitors in the circuit (such as frequency compensation capacitors or load capacitors). Therefore, the output signal needs a certain settling time to complete the step change with the input signal.

[0003] See Figure 2 When the input signal undergoes a step change, the output signal needs a nonlinear settling time and a linear settling time to complete the signal change. In other words, when the input signal changes, the output signal needs to undergo a response time to complete the corresponding change.

[0004] Factors such as the tail current, aspect ratio of the internal input transistor pairs, and parasitic capacitance of an operational amplifier circuit are affected by process variations, causing changes in slew rate and bandwidth, which in turn lead to changes in the output signal response time. To avoid excessive variations in the output signal response time due to process fluctuations, appropriate adjustments to the response time are necessary. Summary of the Invention

[0005] The purpose of this invention is to provide an operational amplifier circuit, its response time adjustment method, and a controller, which can adjust the output response time and avoid excessive changes in the output response time due to process fluctuations.

[0006] This invention proposes an operational amplifier circuit, comprising:

[0007] The first-stage operational amplifier unit amplifies the input signal to generate a first-stage output signal.

[0008] The tail current adjustment circuit generates a first current based on a reference voltage, and adjusts the tail current of the first-level arithmetic unit according to the first current, wherein the tail current is proportional to the first current.

[0009] Specifically, by adjusting the magnitude of the first current, the tail current of the first-stage operational amplifier unit reaches the expected current, and when the input signal changes, the response time of the first-stage output signal reaches the first preset time.

[0010] Optionally, when the response time of the first-stage output signal is greater than the first preset time, the first current is increased to make the tail current of the first-stage operational amplifier unit reach the expected current.

[0011] Optionally, the tail current adjustment circuit includes an auxiliary operational amplifier, an impedance unit, and a current mirror.

[0012] The first input terminal of the auxiliary operational amplifier receives the reference voltage, and its second input terminal and its output terminal are connected to an impedance unit to obtain a first current flowing through the impedance unit.

[0013] The current mirror input receives the first current, and its output current represents the tail current.

[0014] Optionally, the magnitude of the first current can be adjusted by adjusting the magnitude of the reference voltage so that the tail current reaches the expected current.

[0015] Optionally, the magnitude of the first current can be adjusted by adjusting the impedance of the impedance adjustment unit so that the tail current reaches the expected current.

[0016] Optionally, the impedance unit includes a variable resistor, and the impedance is adjusted by adjusting the resistance value of the variable resistor.

[0017] Optionally, the impedance unit includes a first switch, a second switch, and a first capacitor. The first terminal of the first switch is connected to the output terminal of the auxiliary operational amplifier, the second terminal of the first switch is connected to the first terminal of the second switch, the second terminal of the second switch is grounded, and the first capacitor and the second switch are connected in parallel.

[0018] The first switch and the second switch are complementary in conduction, and the impedance of the impedance unit is adjusted by adjusting the switching frequency of the first switch and the second switch.

[0019] Optionally, it also includes a second-stage operational amplifier unit for generating a second-stage output signal based on the first-stage output signal;

[0020] Adjusting the tail current of the second-stage operational amplifier unit according to the first current, so that when the first-stage output signal changes, the response time of the second-stage output signal reaches a second preset time.

[0021] The present invention also provides a method for adjusting an operational amplifier circuit, wherein the operational amplifier circuit performs operational amplification on an input signal to generate an output signal;

[0022] The tail current of the operational amplifier circuit is adjusted to reach the expected current so that when the input signal changes, the response time of the output signal reaches a preset time.

[0023] Optionally, a reference voltage is applied to the impedance unit to generate the tail current;

[0024] The tail current is adjusted to the desired current by adjusting the magnitude of the reference voltage and / or the impedance of the impedance unit.

[0025] The present invention also proposes a controller, including any of the above-described operational amplifier circuits, wherein the controller is connected to the control terminal of the first switch and is used to control the switching state of the first switch.

[0026] Compared with the prior art, the present invention has the following advantages: the operational amplifier circuit amplifies the input signal to generate an output signal; the tail current of the operational amplifier circuit is adjusted to reach the expected current so that when the input signal changes, the response time of the output signal reaches the preset time, thus avoiding the influence of process changes on the response time. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of an existing operational amplifier circuit;

[0028] Figure 2 The output signal response waveform of the operational amplifier circuit is shown.

[0029] Figure 3 This is a schematic diagram of Embodiment 1 of the operational amplifier circuit of the present invention;

[0030] Figure 4 This is a schematic diagram of Embodiment 2 of the operational amplifier circuit of the present invention;

[0031] Figure 5 This is a schematic diagram of Embodiment 1 of the impedance unit of the present invention;

[0032] Figure 6 This is a schematic diagram of Embodiment 2 of the impedance unit of the present invention;

[0033] Figure 7 This is a structural diagram of an embodiment of the computing unit of the present invention. Detailed Implementation

[0034] 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.

[0035] 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.

[0036] See Figure 2The nonlinear settling time is a function of the slew rate of the operational amplifier circuit, while the linear settling time is a function of the bandwidth. Both the slew rate and bandwidth are proportional to the tail current of the operational amplifier circuit. Therefore, by adjusting the magnitude of the tail current, the nonlinear and linear times of the operational amplifier circuit can be adjusted, i.e., the output response time can be adjusted. When the slew rate and bandwidth of some transistors, capacitors, or resistors within the operational amplifier circuit deviate from the expected values ​​due to manufacturing processes, resulting in a deviation from the expected output response time, this invention adjusts the magnitude of the tail current, such as adjusting it to the expected value, to achieve the expected output response time.

[0037] See Figure 3 The diagram illustrates the schematic of Embodiment 1 of the operational amplifier circuit of the present invention, including a tail current adjustment circuit 01 and an operational amplifier unit 02. The tail current adjustment circuit generates an adjustable current signal to adjust the tail current of the operational amplifier unit. The tail current adjustment circuit 02 includes an auxiliary operational amplifier 101, an impedance unit 102, and a current mirror 103. The non-inverting input terminal of the auxiliary operational amplifier receives a reference voltage Vref, and its inverting input terminal and output terminal (point A in the diagram) are connected to the first terminal of the impedance unit. The second terminal of the impedance unit is grounded. According to the virtual short characteristic of the operational amplifier, the voltage of the impedance unit is made equal to the reference voltage. The current I1 flowing through the impedance unit serves as the input current of the current mirror. The current mirror amplifies / replicates the current I1 of the impedance unit according to a certain ratio to obtain the current Ii. S1 Current I S1 Characterizing the magnitude of the tail current by using the current I S1 Further mirroring and amplification yields the tail current. Operational amplifier unit 02 processes the input signals Vp and Vn to obtain the output signal Vout1. When the input signals Vp and / or Vn change (e.g., a step change), the output signal Vout1 will have a certain response time (output response time). The magnitude of the tail current can be adjusted by adjusting the magnitude of the reference voltage Vref and / or the impedance of the impedance unit. For example, adjusting the reference voltage and / or the impedance of the impedance unit to the corresponding value can adjust the tail current to the expected current, making the output response time reach the expected time. For instance, if the output response time is greater than the expected time, the tail current can be increased until the output response time reaches the expected time. This can be achieved by increasing the magnitude of the reference voltage or decreasing the impedance of the impedance unit to increase the current I1, thereby increasing the tail current.

[0038] See Figure 4 The schematic diagram illustrates the principle of Embodiment 2 of the operational amplifier circuit of the present invention. Figure 3Based on the illustrated embodiment 1, the operational amplifier circuit further includes an operational amplifier unit 03, which is cascaded with operational amplifier unit 02. The output signal Vout1 of operational amplifier unit 02 serves as the input signal of operational amplifier unit 03. The current mirror 103 generates current I based on the reflection of current I1. S1 and current I S2 These represent the tail currents of operational amplifier units 02 and 03, respectively. By adjusting the magnitude of the tail currents of the two operational amplifier units, the output response time of the entire operational amplifier circuit can reach the expected time.

[0039] See Figure 5 The diagram illustrates the principle of Embodiment 1 of the impedance unit. The impedance unit includes a variable resistor. The size of the impedance unit is adjusted by adjusting the resistance value of the variable resistor, thereby adjusting the size of the current I1 to achieve the adjustment of the tail current.

[0040] See Figure 6 The diagram illustrates the principle of Embodiment 2 of the impedance unit. The impedance unit includes switches S1 and S2 connected between point A and the ground terminal. Capacitor C1 and switch S2 are connected in parallel, with switches S1 and S2 conducting complementaryly. When switch S1 is on and S2 is off, capacitor C1 charges. When switch S1 is off and S2 is on, the charge on capacitor C1 discharges to ground, reaching zero. Based on the charging and discharging of the capacitor, V1 × C1 = I1 × T, where T = 1 / F, T is the switching period of switches S1 and S2, F is the switching frequency, V1 is the voltage across capacitor C1, and I1 is the average current of the capacitor. Therefore, I1 = V1 × (F × C1). Thus, the impedance circuit is equivalent to a resistor with a resistance of 1 / (F × C1). By adjusting the switching frequency F, the equivalent resistance of the impedance circuit can be adjusted, thereby adjusting the tail current. This invention allows for the determination of the output response time by adjusting the tail current, ensuring that the output response time is independent of process variations.

[0041] See Figure 7 The diagram illustrates the structure of the operational amplifier unit. Transistors M1 and M2 (assuming they are the same size) form a current mirror. The current in transistor M1 is equal to the current in transistor M2 (the tail current of the operational amplifier circuit / op-amp unit). The operational amplifier unit is connected to the output terminal of the tail current adjustment unit. The current flowing through transistor M1 is the output current I of the tail current adjustment unit. S1 Transistors M3 and M4 are a pair of transistors that receive input signals Vp and Vn. Transistors M5 and M6 are connected to transistors M3 and M4 respectively, and capacitor C is connected to the common connection terminal of transistors M4 and M6. L Capacitor C L The voltage is the output voltage of the operational amplifier circuit / operation unit. This block diagram is only an embodiment of the operation unit, used to illustrate how the tail current is regulated, and is not intended to limit the specific structure of the operation unit.

[0042] 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 simplified and use non-precise proportions to facilitate and clearly illustrate the embodiments of the invention.

[0043] 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 embodiment that is described can be referred to.

[0044] 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, include: The first-stage operational amplifier unit amplifies the input signal to generate a first-stage output signal. The tail current adjustment circuit generates a first current based on a reference voltage, and adjusts the tail current of the first-level arithmetic unit according to the first current, wherein the tail current is proportional to the first current. Specifically, by adjusting the magnitude of the first current, the tail current of the first-stage operational amplifier unit reaches the expected current, and when the input signal changes, the response time of the first-stage output signal reaches the first preset time.

2. The operational amplifier circuit according to claim 1, characterized in that: When the response time of the first-stage output signal is greater than the first preset time, the first current is increased to make the tail current of the first-stage operational amplifier unit reach the expected current.

3. The operational amplifier circuit according to claim 1, characterized in that: The tail current adjustment circuit includes an auxiliary operational amplifier, an impedance unit, and a current mirror. The first input terminal of the auxiliary operational amplifier receives the reference voltage, and its second input terminal and its output terminal are connected to an impedance unit to obtain a first current flowing through the impedance unit. The current mirror input receives the first current, and its output current represents the tail current.

4. The operational amplifier circuit according to claim 3, characterized in that: The magnitude of the first current is adjusted by adjusting the magnitude of the reference voltage so that the tail current reaches the expected current.

5. The operational amplifier circuit according to claim 3, characterized in that: The magnitude of the first current is adjusted by regulating the impedance of the impedance adjustment unit so that the tail current reaches the expected current.

6. The operational amplifier circuit according to claim 5, characterized in that: The impedance unit includes a variable resistor, and the impedance is adjusted by adjusting the resistance value of the variable resistor.

7. The operational amplifier circuit according to claim 5, characterized in that: The impedance unit includes a first switch, a second switch, and a first capacitor. The first terminal of the first switch is connected to the output terminal of the auxiliary operational amplifier, the second terminal of the first switch is connected to the first terminal of the second switch, the second terminal of the second switch is grounded, and the first capacitor and the second switch are connected in parallel. The first switch and the second switch are complementary in conduction, and the impedance of the impedance unit is adjusted by adjusting the switching frequency of the first switch and the second switch.

8. The operational amplifier circuit according to claim 1, characterized in that: It also includes a second-stage operational amplifier unit, used to generate a second-stage output signal based on the first-stage output signal; Adjusting the tail current of the second-stage operational amplifier unit according to the first current, so that when the first-stage output signal changes, the response time of the second-stage output signal reaches a second preset time.

9. A method for adjusting an operational amplifier circuit, characterized in that: The operational amplifier circuit amplifies the input signal to generate an output signal. The tail current of the operational amplifier circuit is adjusted to reach the expected current so that when the input signal changes, the response time of the output signal reaches a preset time.

10. The adjustment method according to claim 9, characterized in that: A reference voltage is applied to the impedance unit to generate the tail current; The tail current is adjusted to the desired current by adjusting the magnitude of the reference voltage and / or the impedance of the impedance unit.

11. A controller, characterized in that: The circuit includes any one of the operational amplifier circuits described in claims 1-8, wherein the controller is connected to the control terminal of the first switch and is used to control the switching state of the first switch.

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