Differential wide temperature range CMOS interface circuit for capacitive MEMS pressure sensors

Area of Science:

• Integrated Circuit Design
• Micro-Electro-Mechanical Systems (MEMS)
• Sensor Electronics

Background:

• Capacitive Micro-Electro-Mechanical Systems (MEMS) pressure sensors require specialized interface circuitry.
• Operating temperature extremes can significantly degrade sensor performance and circuit stability.
• Existing interface circuits often lack functionality over a wide temperature range.

Purpose of the Study:

• To develop a Complementary Metal-Oxide Semiconductor (CMOS) differential interface circuit for capacitive MEMS pressure sensors.
• To ensure the circuit's functionality and stability across a broad temperature range (-55°C to 225°C).
• To address performance degradation issues at high temperatures using advanced biasing techniques.

Main Methods:

• Implementation using IBM 0.13 μm CMOS technology with a 2.5 V power supply.
• Application of a constant-gm biasing technique to maintain performance at elevated temperatures.
• Design flexibility to interface with MEMS sensors having steady-state capacitance values from 0.5 pF to 10 pF.

Main Results:

• Simulations demonstrated excellent linearity and stability over the specified wide temperature range.
• Experimental validation confirmed minimal temperature effects on the circuit's performance.
• Achieved an overall linearity error of approximately 2% across the operational temperature spectrum.

Conclusions:

• The developed CMOS interface circuit provides a stable and linear solution for MEMS pressure sensors operating in extreme thermal environments.
• The constant-gm biasing technique effectively mitigates high-temperature performance degradation.
• This circuit design offers a versatile and reliable interface for a wide range of capacitive MEMS pressure sensors.