A High Dynamic Range CMOS-MEMS Accelerometer Array with Drift Compensation and Fine-Grain Offset Compensation

This paper presents a high dynamic range CMOS-MEMS capacitive accelerometer. An array of small masses enables the accelerometer to survive and measure high-G (kG) acceleration. A fine-grain offset compensation technique suppresses the offset due to sense capacitance mismatch. The key idea is to employ two out of 184 accelerometer cells to tune out the charge imbalance, which ensures 90X improved tuning resolution (sub-aF offset). Multiple temperature sensors are integrated on the same accelerometer chip to improve the accelerometer long-term bias instability. The prototype is fabricated in standard 0.18 μm CMOS process and then post-processed to release the accelerometer sensing structures. Measurement results demonstrate that the accelerometer achieves 5.06μV/G transducer scale factor, sub-aF offset, 4.4 μG√hr velocity random walk (VRW), and 5.2 mG bias instability. The sensor array gun-launched at 50 kG and has demonstrated high-shock survivability. Offset measurement results demonstrate 90X better offset tuning resolution than conventional technique.