High-linearity sigma-delta closed loop accelerometer interface circuit

Abstract

The invention discloses a high-linearity sigma-delta closed loop accelerometer interface circuit and belongs to the field of MEMS inertial components. The problems that an existing sigma-delta closed loop accelerometer interface circuit is low in loop gain, a sensitive structural weight block is large in displacement, so that charge voltage converting nonlinearity is increased, and an output signal harmonic component is enhanced are solved. A micro-machine accelerometer sensitive structure is connected with a phase compensation circuit, a first-level integrator circuit, a second-level integrator circuit, a summing circuit and a comparator through a charge detecting / correlated double sampling hold circuit. An output end of the comparator is connected with a weight block feedback end of the micro-machine accelerometer sensitive structure. The output end of the comparator outputs a system bit stream signal. Compared with a traditional feedback structure, system loop gain is greatly improved, static feedback force is increased, weight block displacement is reduced, nonlinearity of a signal detecting and processing circuit is lowered, and the performance of the sigma-delta closed loop accelerometer interface circuit is improved.

Description

technical field [0001] The invention is applicable to the field of MEMS inertial devices and relates to a highly linear Σ-Δ closed-loop accelerometer interface circuit. Background technique [0002] In the field of MEMS inertial devices, due to the technical advantages of integrating MEMS technology and IC technology, capacitive micro-mechanical acceleration sensors have been widely recognized and applied. In the existing various high-order micromachined Σ-Δ accelerometer interface circuits, when the low-frequency gain of the mechanical structure is low, the loop gain is low due to the inherent system structure defects of the interface circuit, which reduces the effect of closed-loop applications . The low loop gain of the system will lead to an increase in the displacement of the mass block of the mechanical structure, which will increase the nonlinearity of the charge conversion process, increase the harmonic component of the system output, reduce the performance of the s...

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to solve the inherent system structural defects of the current Σ-Δ closed-loop accelerometer interface circuit, resulting in low loop gain, large displacement of the mass block of the mechanical structure, high nonlinearity of the charge conversion process, and large harmonic components output by the system , not suitable for the problem of low-frequency gain of the mechanical structure, providing a highly linear Σ-Δ closed-loop accelerometer interface circuit

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