一种可实现增益、带宽独立调控的低噪声MEMS加速度计接口电路设计

A Low-Noise MEMS Accelerometer Interface Circuit Design that Enables Independent Regulation of Gain and Bandwidth

关键词:  前端放大接口电路  噪声  带宽  硅微振梁式加速度计

Key words:  Front-end amplification interface circuit  Noise  Bandwidth  Vibrating beam accelerometer

摘要:

为了进一步满足振梁式加速度计（VBA）对前端放大接口电路增益、带宽以及噪声的更高要求，提出了一种适用于硅微振梁式加速度计的可实现增益、带宽独立调控的低噪声前端放大接口电路。该设计基于T型接口电路的两级拓扑结构，有效解决了增益、带宽和噪声之间的制约问题。通过仿真与实验结果表明，该设计在等效跨阻增益为40MΩ的前提下，最终实现了带宽为410kHz、相位误差为1.2°、等效输入电流噪声密度为8.9fA/Hz。基于该设计的实验样机在上电稳定后1h零偏不稳定性达1.156μg，相较于传统一级跨阻接口电路减小了49.2%（2.274μg），验证了该新型接口电路的可行性和优越性。

Abstract:

In order to further meet the higher requirements of gain, bandwidth and noise of front-end amplifier interface circuit for vibrating beam accelerometer, a low-noise front-end amplifier interface circuit that can realize independent control of gain and bandwidth is proposed. The design is based on the two-stage topology of T-type interface circuit, which effectively solves the constraints among gain, bandwidth and noise. The simulation and experimental results show that the design achieves a bandwidth of 410kHz, a phase error of 1.2°, and an equivalent input current noise density of 8.9fA/Hz on the premise of equivalent transimpedance gain of 40MΩ. The zero bias instability of the experimental prototype based on this design reaches 1.156μg at 1h after the prototype is powered on and stabilized. Compared with the traditional one-stage transimpedance interface circuit, the zero bias instability is reduced by 49.2% (2.274μg), which verifies the feasibility and superiority of the new interface circuit.