Inside Silicon Designs MEMS Accelerometer Technology

How It Works: Capacitance-Based MEMS Sensing

The ASIC reads these changes using a switched-capacitor amplifier, converting micro-level deflections into a voltage signal that spans ±4V, linearly proportional to the applied acceleration.

Why Choose a Silicon Designs MEMS DC Accelerometer?

Continuous DC Response

Unlike piezoelectric sensors, which require dynamic movement to generate a signal, Silicon Designs’ powered MEMS accelerometers can sense motion, or lack thereof, continuously. They provide accurate output even at 0 Hz (static) conditions, ideal for tilt sensing and slow-changing motion.

Minimal Temperature Sensitivity

Capacitive sensing is naturally more stable under temperature variation than resistive-based methods. Combined with the differential wing design, SDI accelerometers cancel out many thermally induced errors, making them highly stable across wide temperature ranges without needing extensive correction.

Lowest Noise in Class

Silicon Designs engineers every MEMS sense element in-house, optimizing each geometry for its specific g-range. Slower, dampened wings for low-g models and faster, flexible wings for high-g models minimizes ASIC gain adjustments and contributes to the industry’s lowest noise levels.

The Engineering Behind the Sensor

The MEMS Sense Element

Each MEMS structure consists of two moving silicon wings arranged in mirror symmetry, suspended over four lower capacitor plates. This fully active capacitive bridge enables high-fidelity differential sensing. By placing the mass off-center and attaching it via torsion bars, the structure is finely tuned for maximum sensitivity, linearity, and minimal cross-axis interference.

This design is fabricated in-house at SDI’s MEMS cleanroom facility in Kirkland, Washington, a process the company has refined for over 30 years.

The ASIC: Capacitance-to-Voltage Conversion

SDI’s custom CMOS ASIC is engineered specifically to convert low-level capacitance changes into a high-level analog voltage. Using a switched-capacitor amplifier, the ASIC modulates fixed voltages across the moving capacitor plates. As the plates move due to acceleration, the resulting voltage is demodulated, amplified, and output as a low-impedance differential signal (AOP – AON).

The ASIC’s integrated PROM and D/A converters allow for calibration at the chip level, adjusting for bias and scale factor tolerances during production. Its internal buffer amplifiers provide high drive strength and excellent noise rejection, eliminating the need for external signal conditioning.

Signal Output Range

The differential output spans ±4 volts:

• +4V = Positive full-scale acceleration
• –4V = Negative full-scale acceleration
• 0V = Zero acceleration

This wide range allows for high-resolution output, ideal for integration with DAQ systems and embedded platforms.