Analog CMOS design for optical coherence tomography signal detection and processing.

Area of Science:

• Integrated Circuit Design
• Biomedical Optics
• Optical Coherence Tomography

Background:

• Optical Coherence Tomography (OCT) requires sophisticated signal detection and processing.
• Existing OCT systems often involve complex and bulky electronics.
• Advancements in CMOS technology offer potential for miniaturized and efficient OCT signal processing.

Purpose of the Study:

• To design and fabricate a compact CMOS circuit for OCT signal detection and processing.
• To enable accurate extraction of interferometric signal envelopes and phase information.
• To facilitate Doppler OCT measurements with high sensitivity and signal fidelity.

Main Methods:

• A CMOS circuit integrating a photoreceiver, differential gain stage, and lock-in amplifier demodulator was designed and fabricated.
• The photoreceiver includes a CMOS photodetector and a low-noise differential transimpedance amplifier.
• The lock-in amplifier utilizes analog mixers and switched-capacitor low-pass filters for in-phase and quadrature channel processing.

Main Results:

• The fabricated CMOS circuit achieved a sensitivity of -80 dB.
• Faithful reproduction of the interferometric signal envelope was demonstrated.
• The circuit successfully enabled extraction of signal envelope and phase, suitable for Doppler OCT.

Conclusions:

• A functional CMOS circuit for OCT signal detection and processing has been successfully designed and fabricated.
• The integrated circuit provides high sensitivity and accurate signal reproduction, suitable for Doppler OCT.
• This development paves the way for more compact and efficient OCT systems.