Low-noise amplifier applied to acceleration sensor

Abstract

The invention belongs to the technical field of low-noise amplifiers, and particularly relates to a low-noise amplifier applied to an acceleration sensor. The amplifier comprises two stages of amplifiers, a modulator and a demodulator. The first stage adopts a folded cascode structure to improve input impedance, meanwhile, the modulator is additionally arranged at an input port to modulate a signal to high frequency to avoid interference of low-frequency flicker noise and direct-current offset voltage, meanwhile, the demodulator is used for recovering signals at the output of the first stage, low-frequency flicker noise and direct-current offset voltage are modulated to high frequency, and finally the low-frequency flicker noise and the direct-current offset voltage are filtered out through an external filter circuit. The second stage adopts a circuit structure of a Class-AB power amplifier to improve the output capability, a floating gate current source controls the quiescent working point of the whole circuit, and the quiescent power consumption of the whole circuit is reduced.

Description

technical field [0001] The invention belongs to the technical field of low-noise amplifiers, and in particular relates to a low-noise amplifier applied to acceleration sensors. Background technique [0002] The output voltage signal of the acceleration sensor is very weak, and because the transistor (MOSFET) will bring flicker noise and thermal noise to the circuit, the traditional CMOS amplifier design method will cause the input signal to be submerged in the noise and cannot be collected and processed, such as figure 1 , At the same time, due to the process error, the random mismatch of the MOSFET parameters is caused by the amplifier to generate an offset voltage, which will cause the microcontroller to make wrong judgments on the output information of the sensor. In order for the signal conditioning circuit of the subsequent stage to correctly process the output signal of the sensor, some circuit techniques are required to reduce the offset voltage and noise of the ampli...

AI Technical Summary

Problems solved by technology

[0002] The output voltage signal of the acceleration sensor is very weak, and because the transistor (MOSFET) will bring flicker noise and thermal noise to the circuit, the traditional CMOS amplifier design method will cause the input signal to be submerged in the noise and cannot be collected and processed, such as figure 1 , and at the same time, due to the random mismatch of MOSFET parameters caused by the process error, the amplifier will generate an offset voltage, which will make the microcontroller make wrong judgments on the output information of the sensor

Images