阅读说明：本技术 运算放大器及其控制方法 (Operational amplifier and control method thereof ) 是由 王文祺 黄思衡 于 2018-04-12 设计创作，主要内容包括：本申请提供了一种运算放大器,其特征在于,包括第一放大级,用来根据多个输入电压产生多个第一输出电压；第二放大级,用来根据所述多个第一输出电压,产生多个第二输出电压；第二输出级电路,用来复制与所述第一输出级电路相同或等比例缩小的电路；第一共模回馈电路,用来将所述第二输出级电路的输出共模电压,维持于一预设值；逻辑回路电路,用来于所述运算放大器于直流校正时,调整所述第一放大级的所述多个第一输出电压的差值；偏压电路,用来产生在运算放大器开启后与所述第一放大级的所述多个第一输出电压的共模电压相近的电压,以作为第二共模回馈电路的参考电压。本申请提供的运算放大器具有降低电压突波,避免产生爆音噪声的优点。(The application provides an operational amplifier, which is characterized by comprising a first amplification stage, a second amplification stage and a third amplification stage, wherein the first amplification stage is used for generating a plurality of first output voltages according to a plurality of input voltages; a second amplification stage for generating a plurality of second output voltages according to the plurality of first output voltages; a second output stage circuit for replicating a circuit that is the same as or scaled down from the first output stage circuit; the first common-mode feedback circuit is used for maintaining the output common-mode voltage of the second output stage circuit at a preset value; a logic loop circuit for adjusting the difference between the first output voltages of the first amplifier stage when the operational amplifier is performing dc calibration; the bias circuit is used for generating a voltage which is close to the common-mode voltage of the plurality of first output voltages of the first amplification stage after the operational amplifier is started, and the voltage is used as a reference voltage of the second common-mode feedback circuit. The operational amplifier provided by the application has the advantages of reducing voltage surge and avoiding the generation of popping noise.)

An operational amplifier, comprising:

a first amplification stage for generating a plurality of first output voltages according to a plurality of first input voltages;

a second amplifier stage coupled to the first amplifier stage for generating a plurality of second output voltages according to the plurality of first output voltages;

a second output stage circuit, coupled to the second amplifier stage and the first output stage circuit, for duplicating a circuit that is the same as or scaled down from the first output stage circuit;

a first common mode feedback circuit, coupled to the second amplifier stage and the second output stage circuit, for maintaining an output common mode voltage of the second output stage circuit at a predetermined value;

a logic loop circuit, coupled to the first amplifier stage, for adjusting a difference between the first output voltages of the first amplifier stage;

a bias circuit for generating a voltage similar to a common-mode voltage of the second input voltages of the second amplifier stage after the operational amplifier is turned on, as a reference voltage of the second common-mode feedback circuit;

a second common mode feedback circuit, coupled to the first amplifier stage, for maintaining an output common mode voltage of the first output voltages of the first amplifier stage at the reference voltage; and

a plurality of switches for controlling the connection of the first amplifier stage, the second amplifier stage, the first output stage circuit, the second output stage circuit, the first common mode feedback circuit, the logic circuit and the second common mode feedback circuit according to a control signal, so that the operational amplifier is in a bias correction stage.

The operational amplifier of claim 1, wherein the output common mode voltage of the second output stage circuit is similar to the output common mode voltage of the operational amplifier after being turned on.

The operational amplifier of claim 1, wherein the first output stage is coupled to a plurality of voltage sources and the second output stage through the plurality of switches, and wherein the first output stage is turned on when the operational amplifier is turned on.

The operational amplifier of claim 1, wherein said first output stage circuit is turned off when said logic circuit adjusts said difference in said plurality of first output voltages of said first amplification stage.

The operational amplifier of claim 1, wherein after the bias correction phase is completed, the difference between the first output voltages of the first amplifier stage approaches zero, the second output stage circuit, the first common mode feedback circuit, the second common mode feedback circuit and the logic circuit are turned off, and the first output stage circuit and the third common mode feedback circuit are turned on.

The operational amplifier of claim 5, wherein the third common mode feedback circuit is coupled to the first amplifier stage and maintains an output common mode voltage of the plurality of output voltages of the operational amplifier at the predetermined value.

A control method is used for a bias correction process of an operational amplifier, wherein the operational amplifier comprises a first amplification stage, a second output stage circuit, a first common mode feedback circuit, a logic circuit, a second common mode feedback circuit and a bias circuit, and is characterized by comprising the following steps:

during bias correction, the second common-mode feedback circuit maintains the output common-mode voltage of the first output voltages of the first amplification stage at a voltage close to the common-mode voltage of the second input voltages of the second amplification stage after the operational amplifier is started;

the first common-mode feedback circuit maintains the output common-mode voltage of the second output stage circuit at a preset value; and

the logic loop circuit adjusts a difference of the first output voltages of the first amplification stage to approach zero.

The control method of claim 7, wherein the second output stage circuit is coupled to the second amplifier stage, and an output common mode voltage of the second output stage circuit is similar to an output common mode voltage of the operational amplifier after being turned on.

The method of claim 7, wherein the operational amplifier further comprises a first output stage circuit that is turned off when the logic circuit adjusts the difference in the first output voltages of the first amplifier stage.

The control method of claim 9, wherein when the difference between the first output voltages of the first amplifier stage is close to zero after the bias voltage calibration is completed, the second output stage circuit, the first common mode feedback circuit, the second common mode feedback circuit and the logic circuit are turned off, and the first output stage circuit and the third common mode feedback circuit are turned on.

The control method of claim 10, wherein the third common mode feedback circuit is coupled to the first amplifier stage and maintains an output common mode voltage of the plurality of output voltages of the operational amplifier at the predetermined value.