A Bond-Wire Drift Offset Minimized Capacitance-to-Digital Interface for MEMS Accelerometer with Gain-Enhanced...

Area of Science:

• Electrical Engineering
• Microelectromechanical Systems (MEMS)

Background:

• MEMS accelerometers require precise capacitance-to-digital interfaces.
• Output offset and limited dynamic range are common challenges in these interfaces.
• Non-ideal factors like bond-wire drift can degrade accelerometer performance.

Purpose of the Study:

• To present a capacitance-to-digital interface for MEMS accelerometers with minimized output offset.
• To improve the dynamic range of the digital output signal.
• To achieve offset cancellation efficiently and cost-effectively.

Main Methods:

• Utilized a gain-enhanced voltage-controlled oscillator (VCO)-based quantization loop.
• Embedded a nested digital chopping feedback loop for output offset minimization.
• Fabricated the interface using a 0.18 μm Global Foundry (GF) CMOS process.

Main Results:

• Achieved a 78 dB dynamic range with 0.4% nonlinearity from a single 2 V supply.
• The offset cancellation loop effectively minimized DC output offset to within 40 mV for input-referred offsets up to 1.3 pF.
• Demonstrated low power dissipation of 6.5 mW with a 4 kHz bandwidth.

Conclusions:

• The proposed interface effectively minimizes output offset in MEMS accelerometers.
• The architecture offers significant improvements in dynamic range and offset reduction.
• The design is suitable for low-cost, high-performance MEMS accelerometer applications.