Small-signal processing low-overhead operational amplifier for delta sigma ADC (Analog to Digital Converter)

Abstract

A small signal processing low-overhead operational amplifier for delta sigma ADC relates to the technical field of analog integrated circuits, and comprises a transistor level circuit, a bias voltage generating circuit and an output CMFB, the bias voltage generating circuit provides grid voltage for transistors, the output CMFB is used for correcting any mismatch in current of differential transistors, and the output CMFB is used for correcting the current of the differential transistors. The transistor level circuit adopts a two-stage cascade structure, and the first stage adopts a gain-enhanced folded cascode structure and small bias current to realize high gain and reduce area overhead; and the second stage adopts a bias current source load common-source structure, large bias current and large overdrive voltage to ensure unit gain bandwidth and reduce area overhead. By improving the transistor-level circuit structure in the operational amplifier, the layout is greatly simplified, the area waste is reduced, and the problem of overlarge area overhead on the premise of high gain and unity gain bandwidth is solved.

Description

technical field [0001] The present invention relates to the technical field of analog integrated circuits, in particular to a small-signal processing low-overhead operational amplifier for ΔΣ ADCs. Background technique [0002] Operational amplifier (Op-Amp) is one of the basic building blocks of analog and mixed-signal integrated circuits, and its performance develops with its application field, currently mainly in three directions of low power consumption, high speed and high gain. For some high-speed and high-precision circuits, such as sample-and-hold circuits, delta-Sigma analog-to-digitalconverter (ΔΣADC), switched capacitor filters, etc., their basic circuit operational amplifiers need to have high-speed and high-gain performance, corresponding to large gain and unity Gain bandwidth (Unity gain bandwidth, UGB), the important role of the operational amplifier in the ΔΣ ADC is to build an integrator, its DC voltage gain A 0 and unity gain bandwidth (UGB) can cause no...

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Problems solved by technology

[0004] Aiming at the deficiencies of the prior art, the present invention provides a small-signal processing low-overhead operational amplifier oriented to ΔΣADC to solve the problem of traditional small-signal processing operational amplifiers oriented to ΔΣADC under the premise of high gain and unity gain bandwidth. The problem of excessive overhead

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