A Power-Efficient Capacitive Read-Out Circuit With Parasitic-Cancellation for MEMS Cochlea Sensors

Area of Science:

• Electrical Engineering
• Biomedical Engineering
• Sensor Technology

Background:

• MEMS cochlea sensors face signal degradation due to small sensing capacitance and parasitic capacitance at the MEMS-CMOS interface.
• Traditional read-out circuits struggle with signal loss in low-capacitance, non-differential MEMS sensors.

Purpose of the Study:

• To develop a novel capacitive read-out circuit for MEMS cochlea sensors.
• To address signal degradation caused by parasitic capacitance.
• To enhance sensor sensitivity and power efficiency.

Main Methods:

• A novel capacitive read-out circuit with a parasitic-cancellation mechanism was designed and implemented.
• The circuit features an adjustable negative equivalent input capacitance to cancel parasitic capacitance.
• Chopper-stabilization technique was employed to reduce low-frequency noise and DC offsets.

Main Results:

• Parasitic-cancellation increased sensor sensitivity by 35 dB without additional power consumption.
• The circuit achieved a low-degradation, low-amplification approach, enhancing power efficiency.
• A prototype chip converted a 7.5 fF capacitance change into a 0.745 V output with 165.2 μW power consumption.

Conclusions:

• The developed read-out circuit effectively cancels parasitic capacitance, significantly boosting MEMS cochlea sensor sensitivity.
• The low-power, high-sensitivity design offers a power-efficient alternative to traditional high-gain approaches.
• This advancement is crucial for improving the performance of MEMS-based auditory sensing technologies.