High-Temperature IEPE Charge Amplifier With Enhanced Low-Frequency Performance for MEMS Piezoelectric Accelerometer

The micro-electromechanical systems (MEMSs) piezoelectric (PE) accelerometers are ideal for extreme environments, such as high temperature, but extracting weak charge signals remains challenging. This article presents for the first time an integrated electronics PE (IEPE) high-temperature MEMS accelerometer, based on a self-developed PE MEMS accelerometer and IEPE charge amplifier. First, a theoretical model was established to evaluate the sensitivity, bandwidth, and noise characteristics of the charge amplifier at elevated temperatures. Meanwhile, the corresponding parameters are obtained by simulation. Second, a high-temperature lower corner frequency test system was established based on the electric excitation discharge time constant (EEDTC) principle, resolving the issue of inadequate load in low-frequency response testing system. Finally, feedback capacitance and bias resistance parameters are optimized to maintain the zero temperature coefficient (ZTC) operating point in the IEPE charge amplifier, reducing low-frequency temperature drift. Above all, the developed IEPE high-temperature MEMS accelerometer achieves a wide 3-dB bandwidth of 0.11–7000 Hz, a sensitivity of 2.72 mV/g, a noise spectral density of $4.45~\mu $ V/ $\surd $ Hz at 10 Hz, a nonlinearity of 0.14% at 500 g, and a transverse sensitivity of 0.42% at room temperature, and it achieves a -3-dB lower corner frequency at 0.24 Hz, a sensitivity of 2.24 mV/g, a noise spectral density of $10~\mu $ V/ $\surd $ Hz at 10 Hz, and an equivalent noise of $\le 0.0278~{g}_{\text {rms}}$ at $175~^{\circ }$ C, which is of significant importance for the application of MEMS PE accelerometers in high-temperature environments.