Low-noise weak signal detection interface circuit capable of realizing independent regulation and control of gain and bandwidth

Abstract

The invention discloses a low-noise weak signal detection interface circuit capable of realizing independent regulation and control of gain and bandwidth. The interface circuit is used for converting a weak detection current signal of a sensor into a voltage signal. The interface circuit comprises two stages of amplification topologies: a first-stage T-type amplifier consisting of a capacitor C1, a parasitic capacitor Cp, a pseudo resistor Rb, a resistor R1, a resistor R2 and a transconductance amplifier OTA1; and the capacitor C2, the capacitor Cc, the resistor Rf and the transconductance amplifier OTA2 form a second-stage transimpedance amplifier. According to the circuit, the gain can be improved by improving the ratio of R2 / R1 and C2 / C1 without increasing Rf, the resistor Rb and the capacitor Cc can independently adjust the bandwidth, and the problem of restriction among the gain, the bandwidth and noise is greatly solved; in addition, the circuit can realize extremely low equivalent input current noise, and the signal-to-noise ratio of a detection current signal is greatly improved.

Description

technical field [0001] The invention belongs to the technical field of sensor interface circuits, in particular to the design of an I-V conversion interface circuit of a MEMS resonant sensor, in particular to a low-noise weak signal detection interface circuit capable of independent control of gain and bandwidth. Background technique [0002] Weak signals are signals that are very small in amplitude or are easily masked by ambient noise. There are many weak signals in practical engineering in various fields, and there is usually a lot of information behind these signals. Therefore, the detection of weak signals becomes particularly important. [0003] Most of the weak signal acquisition work is to use various adapted sensors to realize the acquisition work and convert it into current or voltage. For example, the photoelectric sensor converts the light signal into a weak electrical signal, and then completes the calibration of the measured light signal; the same precision fo...

AI Technical Summary

Problems solved by technology

[0004] For the weak detection current signal, its value is usually at the nA level, which is very susceptible to noise interference or even submerged in the noise, making detection more difficult. Therefore, the low-noise front-end amplifier interface circuit is the key to ensure the measurement accuracy of precision sensors

However, the traditional front-end amplifier is difficult to solve the constraints of gain, bandwidth, noise, power consumption and other indicators

For example, switched capacitor front-end amplifiers suffer from noise aliasing

At the same time, due to the existence of parasitic capacitance, single-stage or multi-stage traditional transimpedance amplifiers are difficult to solve the contradiction between bandwidth, gain and noise

Therefore, the design of the front-end interface circuit is a big challenge

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