Low Noise Feed-Through Compensation Circuit Design for Resonant MEMS Pressure Sensor.

The feed-through effect of resonant pressure sensors usually introduces interfering noise signals, leading to the degradation of sensitivity, linearity, and other performances of the sensor test system. A low-noise charge amplifier and its feed-through compensation circuit are designed to realize high-precision measurements. The designed improved charge amplifier has a differential common-source structure as the output buffer stage, which can effectively reduce the output noise of the circuit while increasing the input impedance, thus improving the accuracy of the feed-through compensation coefficient. By establishing the equivalent circuit model of the sensor and analyzing the influence of the feed-through effect on the sensor test, the feed-through compensation circuit is designed to suppress the feed-through signal. Experimental testing of the sensor proves that the designed circuit can effectively suppress the feed-through effect of the sensor. The noise power spectral density of the improved charge amplifier is tested to be 26.74 nV/√Hz, which is a 65% reduction in noise density. The feed-through compensation circuit eliminates the interference frequency of 34,919 Hz introduced by the feed-through capacitor. Additionally, the resonance peak of the intrinsic resonance frequency of the pressure sensor is -40.75 dBV, which is reduced by 8 dBV compared with that before the feed-through compensation. The feed-through compensation circuit effectively reduces the feed-through interference signal of the sensor, improves the measurement accuracy of the test system, and provides technical support for the design of a low-noise, high-precision, stable, and reliable sensor test system.