Voltage buffer amplifier

Abstract

The invention discloses a voltage buffer amplifier. The voltage buffer amplifier comprises a main amplification circuit and a self-adaption circuit. The size of the working current of the main amplification circuit is determined by a first current sink; the self-adaption circuit provides a mirror current to the first current sink and automatically adjusts the current size of the first current sink based on the working state of the main amplification circuit; when the voltages at the positive-phase and negative-phase input ends are equal, the self-adaption circuit enables the current of the first current sink to be as a first value; when the voltages at the positive-phase and negative-phase input ends are different, the self-adaption circuit enables the current of the first current sink to be as a second value; the first value is less than the second value; the power consumption of the voltage buffer amplifier is reduced through the relatively small first value; and the charging and discharging speed of the output end of the voltage buffer amplifier is increased through the relatively big second value, and the slew rate is accordingly increased. According to the voltage buffer amplifier, the slew rate and the building speed of the voltage buffer amplifier are increased, the stabilizing time of the voltage buffer amplifier can be reduced, and the power consumption also can be decreased.

Description

technical field [0001] The invention relates to a semiconductor integrated circuit, in particular to a voltage buffer amplifier. Background technique [0002] A voltage buffer is usually used to provide the voltage required for circuit operation to enhance its driving capability, and at the same time prevent the load from affecting the output voltage of the voltage buffer. [0003] The voltage buffer can provide the common-mode voltage required for the sampling phase in the successive approximation analog-to-digital converter, but this common-mode voltage is not needed during the conversion phase, and the voltage buffer can be turned off during the conversion phase in order to save power consumption. [0004] This limits the speed of the ADC due to the time it takes for the voltage buffer to settle and stabilize. In addition, in order for the buffer to quickly establish and stabilize when driving other modules, the buffer must have a large enough slew rate and bandwidth, wh...

AI Technical Summary

Problems solved by technology

[0004] Due to the time required for the voltage buffer to settle and stabilize, this limits the speed of the ADC

In addition, in order for the buffer to quickly establish and stabilize when driving other modules, the buffer must have a large enough slew rate and bandwidth, which forces the buffer to have a large quiescent current, which causes the voltage buffer circuit to occupy A large power consumption of the entire analog-to-digital converter

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