Reconfigurable Sensor Analog Front-End Using Low-Noise Chopper-Stabilized Delta-Sigma Capacitance-to-Digital...

Area of Science:

• Analog electronics
• Sensor interfaces
• Mixed-signal integrated circuits

Background:

• Capacitive microsensors are crucial for various applications but often require complex interface circuitry.
• Low-frequency noise, such as offset and flicker noise, significantly degrades the performance of sensor analog front-ends.
• Reconfigurable front-ends are needed for multi-mode applications to handle diverse sensor types and signal levels.

Purpose of the Study:

• To propose and validate a reconfigurable sensor analog front-end.
• To achieve low-noise performance for capacitive microsensors using chopper stabilization.
• To enable direct conversion of both capacitive and voltage signals without a dedicated amplifier.

Main Methods:

• Design of a low-noise chopper-stabilized delta-sigma capacitance-to-digital converter (CDC).
• Implementation of a reconfigurable architecture capable of interfacing with capacitive microsensors and voltage signals.
• Integration of a temperature sensor for enhanced functionality.
• Fabrication using a standard 0.18-μm CMOS process.

Main Results:

• The prototype chip achieves an effective resolution of 16.3-bit.
• Low-noise performance is demonstrated through chopper stabilization, reducing low-frequency noise.
• The front-end successfully drives both capacitive microsensors and voltage signals directly.
• Total power consumption is measured at 0.843 mW with a 1.8 V supply.

Conclusions:

• The proposed reconfigurable sensor analog front-end offers a high-resolution, low-noise solution for capacitive microsensors.
• The direct conversion capability and multi-mode support make it suitable for diverse applications.
• The integrated design in a standard CMOS process demonstrates practical feasibility and efficiency.