Analog CMOS design for optical coherence tomography signal detection and processing. |
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Authors: | Wei Xu David L Mathine Jennifer K Barton |
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Affiliation: | High Performance Analog Division, Texas Instruments, Tucson, AZ 85706, USA. vpecxuwei@gmail.com |
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Abstract: | A CMOS circuit was designed and fabricated for optical coherence tomography (OCT) signal detection and processing. The circuit includes a photoreceiver, differential gain stage and lock-in amplifier based demodulator. The photoreceiver consists of a CMOS photodetector and low noise differential transimpedance amplifier which converts the optical interference signal into a voltage. The differential gain stage further amplifies the signal. The in-phase and quadrature channels of the lock-in amplifier each include an analog mixer and switched-capacitor low-pass filter with an external mixer reference signal. The interferogram envelope and phase can be extracted with this configuration, enabling Doppler OCT measurements. A sensitivity of -80 dB is achieved with faithful reproduction of the interferometric signal envelope. A sample image of finger tip is presented. |
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