High-Update-Rate Frequency Readout of Sinusoidal Signals for Silicon Resonant Accelerometers Using Digital...

Area of Science:

• Sensor Technology
• Signal Processing
• Microelectromechanical Systems (MEMS)

Background:

• Silicon resonant accelerometers provide acceleration data via frequency shifts in sinusoidal outputs.
• Conventional readout methods face quantization errors at high update rates due to timing limitations.

Purpose of the Study:

• To develop and evaluate a high-update-rate frequency readout method for sinusoidal resonant signals.
• To overcome the limitations of conventional counting-based readout techniques.

Main Methods:

• A novel frequency reconstruction method using quadrature demodulation and phase extraction from the sinusoidal signal.
• Implementation of a Phase-Locked Loop (PLL) and Frequency-Locked Loop (FLL) cooperative loop on a Zynq-7020 platform for signal acquisition.
• Prototype-level evaluation focusing on readout principle and FPGA implementation.

Main Results:

• The proposed method demonstrates a lower theoretical quantization limit compared to synchronous multi-cycle counting at 1 kHz update rate.
• Reduced standard deviation of zero-bias output from 4.1 μg to 2.4 μg over a 1800-5400 s period.
• Decreased frequency-difference peak-to-peak value from 0.03743 Hz to 0.02410 Hz under steady-state conditions.

Conclusions:

• The developed phase-based readout method is feasible and valuable for high-update-rate applications.
• The method effectively reduces noise and improves the stability of resonant accelerometer outputs.
• This advancement supports more accurate acceleration sensing in demanding applications.