Low-voltage and low-power dissipation pseudo-two stage Class-AB OTA structure

Abstract

The invention relates to a low-voltage low-power-consumption false two-stage Class-AB OTA structure, belonging to low-voltage low-power-consumption calculation amplifier technical field, as one current mirror Class-AB output stage of calculation amplifier in alternative control, which is composed of an alternative control input stage, a Class-AB output stage, a bias output stage, and a frequency compensation portion. The invention uses false two-stage Class-AB structure, and accurately controls tail current source and bias current to increase open-loop direct-current increment without changing the size of input transistor. The invention can realize high-increment high-bandwidth output amplitude design used in switch capacitor, at low-voltage low-power-consumption system. The current mirror Class-AB output stage can reduce circuit power consumption as well as increase output amplitude. The bias circuit can increase the power supply restrain ratio of circuit. And the invention uses dual-input alternative control to process frequency compensation, improve circuit stability, and reduce the value of compensation capacitor.

Description

technical field [0001] The invention belongs to the scope of switched capacitor circuits, and in particular relates to a low-voltage, low-power consumption pseudo-two-stage Class-AB OTA structure directly applied to low-voltage and low-power switched capacitor circuits and suitable for low-voltage and low-power integrator circuits. Background technique [0002] High-performance operational amplifiers are the most basic building blocks of switched capacitor circuits and are widely used in analog filters and oversampling sigma-delta analog-to-digital converters. With the continuous progress of technology, the power supply voltage is continuously reduced. In order to meet the bandwidth requirements, it is often necessary to increase the current of the circuit, which increases the total power consumption of the circuit. [0003] Figure 1 and Figure 2 respectively show the traditional current mirror output OTA structure and the two-stage Class-AB output OTA structure, which are w...

AI Technical Summary

Problems solved by technology

However, the introduction of a small non-dominant pole in the two-stage structure reduces the phase margin of the circuit, and the circuit is not easy to stabilize

The input transistors M5--M8 of the Class-AB output stage are closely related to the power supply and ground, so that the noise from the power supply and ground in the entire chip directly affects the performance of the circuit, resulting in unstable circuit performance or even failure

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