关键词: 平均光电流检测, 输出失调存储, 光通信

Abstract: In high speed optical communication system, the received signal strength is variable with distance or fiber loss. Thus the average photocurrent should be detected to determine the optical power, and change gain of amplifier correspondingly. The amplifier is then operating properly without saturation or less gain. Average photocurrent detector circuit is proposed in this paper. By clamping cathode of the photo diode to detection circuit , the average photocurrent is then detected. In order to eliminate derivation caused by random offset, output offset storage (OOS) technique is adopted in this paper. The output offset voltage is sampled and held by S/H circuit, and offset current is then generated to compensate the output offset current of the main amplifier. Consequently, the detection accuracy is improved. The average photocurrent detector proposed in the paper is designed and fabricated by 0. 18 μm CMOS process. Measurement results show that 7. 5% detection accuracy is realized for 1. 25 Gbps optical receiver.

Key words: average photocurrent detection, output offset voltage storage, optical communication