Xu Wei, Mathine David L, Barton Jennifer K
High Performance Analog Division, Texas Instruments, Tucson, AZ 85706, USA.
IEEE Trans Biomed Eng. 2008 Feb;55(2 Pt 1):485-9. doi: 10.1109/TBME.2007.905402.
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.
设计并制造了一种用于光学相干断层扫描（OCT）信号检测与处理的CMOS电路。该电路包括一个光接收器、差分增益级和基于锁相放大器的解调器。光接收器由一个CMOS光电探测器和低噪声差分跨阻放大器组成，该放大器将光干涉信号转换为电压。差分增益级进一步放大信号。锁相放大器的同相和正交通道各包括一个模拟混频器和带有外部混频器参考信号的开关电容低通滤波器。利用这种配置可以提取干涉图包络和相位，从而实现多普勒OCT测量。在忠实地再现干涉信号包络的情况下，实现了-80 dB的灵敏度。给出了指尖的样本图像。
