Although one of the poster children of high-performance MEMS (Micro Electro Mechanical Systems) gyroscopes, the MEMS hemispherical resonator gyroscope (HRG) is faced with the barrier of technical and process limits, which makes it unable to form a resonator with the best structure. How to obtain the best resonator under specific technical and process limits is a significant topic for us. In this paper, the optimization of a MEMS polysilicon hemispherical resonator, designed by patterns based on PSO-BP and NSGA-II, was introduced. Firstly, the geometric parameters that significantly contribute to the performance of the resonator were determined via a thermoelastic model and process characteristics. Variety regulation between its performance parameters and geometric characteristics was discovered preliminarily using finite element simulation under a specified range. Then, the mapping between performance parameters and structure parameters was determined and stored in the BP neural network, which was optimized via PSO. Finally, the structure parameters in a specific numerical range corresponding to the best performance were obtained via the selection, heredity, and variation of NSGAII. Additionally, it was demonstrated using commercial finite element soft analysis that the output of the NSGAII, which corresponded to the Q factor of 42,454 and frequency difference of 8539, was a better structure for the resonator (generated by polysilicon under this process within a selected range) than the original. Instead of experimental processing, this study provides an effective and economical alternative for the design and optimization of high-performance HRGs under specific technical and process limits.

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.

In order to improve the performance of MEMS resonant pressure sensors, it is important to design a transimpedance amplifier (TIA) circuit with high gain, low noise and stability. A novel ultra-low noise TIA topology is proposed to be used as an interface circuit for sensors. The new TIA topology greatly relaxes the trade-off among gain, bandwidth and noise. An input reference current noise density of 3.25 fA Hz − 1 is achieved, and the new TIA structure eliminates the DC bias introduced by the noiseless capacitor feedback network. The TIA topology also achieves 50 M Ω transimpedance gain. For circuit validation, a closed-loop system based on phase-locked loop detection is used in this paper. In this paper, a pressure sensor compatible with the vibration pattern of a wide detection cell and the sensitivity of a narrow detection cell is tested. The sensor system is tested to validate the effectiveness of the proposed TIA, demonstrating a noise floor of 5 μ V , a pressure response of 73.69 Hz Hz kPa kPa − 1 , and linearity of 0.99999.

The low-noise charge detection circuit is crucial for the precision of a gyroscope system. Traditional three-op-amp differential charge amplifier suffer from high noise and power consumption, whereas single-op-amp charge amplifier exhibit limited common-mode rejection performance. To improve the noise performance and common mode rejection ratio (CMRR) of differential charge amplifiers, an enhanced differential charge amplifier has been recently introduced. This paper presents an enhanced single-op-amp differential charge amplifier featuring a fully differential common-source structure as the input buffer stage. The input buffer stage is engineered to minimize input noise, maintain a high input impedance, and enhance the CMRR of the circuit. Utilizing the architecture of the enhanced differential charge amplifier, this study develops an equivalent noise model and meticulously analyzes the noise sources, thereby substantiating the efficacy of the structure in diminishing input noise. The designed charge amplifier is experimentally verified to have demonstrated an overall charge gain of 9 V/pC and an input-referred RMS charge noise of 142.2 aC, with a −3 dB passband width of 18 Hz–810 kHz. The CMRR consistently achieves a maximum of 54.5 dB, thereby effectively suppressing the common-mode noise. The enhanced circuit proposed herein possesses an ultra-low noise floor and a high signal-to-noise ratio and exhibits rapid response characteristics, thereby markedly attenuating system noise and precisely tracking the dynamically varying charge signals. This enhancement leads to a substantial improvement in the measurement precision of toroidal gyroscope test systems. The findings of this study also offer a novel approach to the design of low-noise, high-gain, and high-precision differential charge amplifiers.