Extremely low noise nested chopper-stabilized amplifier based on cmos devices

Abstract

The invention discloses an extremely low-noise nested chopper-stabilized amplifier based on CMOS devices, comprising a differential input pair composed of PMOS transistors, an output impedance stage composed of a folded cascode, a source negative feedback current source, and a The chopper switch composed of PMOS or NMOS transistors, the differential input pair composed of PMOS transistors realizes the function of converting the input voltage signal into a current signal; the output impedance stage composed of folded cascode provides high output impedance for the amplifier; The formed current source provides a constant bias current for the amplifier; the source degeneration resistor provides local feedback to suppress the white noise and 1 / f noise generated by the current source; the negative effect of charge injection is reduced by nested chopping, and at the same time Chopping is enhanced for very low noise performance. The present invention has the same level of noise performance, reduces power consumption from mA to μA level, is easy to integrate, and has low cost.

Description

technical field [0001] The invention relates to the technical field of analog integrated circuits, in particular to an extremely low-noise nested chopper-stabilized amplifier based on a CMOS device. Background technique [0002] Operational amplifiers are the most important circuit units in analog circuits, and are widely used in analog circuits and mixed signal processing circuits, such as amplifier circuits, switched capacitors, analog-to-digital, digital-to-analog converters, etc. In the field of low-frequency applications, operational amplifiers are often required to have low offset, low noise and other characteristics, such as instrumentation amplifiers, low-speed high-precision analog-to-digital converters, etc. Bipolar transistors have a high transconductance current ratio and can provide high transconductance and gain; bipolar transistors have very low offset and 1 / f noise because they have no threshold effect and have a large area. Therefore, bipolar technology is ...

AI Technical Summary

Problems solved by technology

[0007] 1. The traditional bipolar technology amplifier occupies a large chip area, high cost, high power consumption, and is not easy to integrate; it is not suitable for new application requirements

[0008] 2. Chopping at high resistance points will limit the chopping frequency and cause gain loss; nested chopping at high resistance points will further limit the chopping frequency and signal bandwidth

[0009] 3. Low-resistance point chopping is a kind of local chopping, and the chopping effect is limited

[0010] 4. Single-stage chopping has limited effect on noise suppression. Under the same noise floor requirement, a larger current is required, thus consuming more power consumption

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