A 5-Gb/s Noise Optimized Receiver Using a Switched TIA for Wireless Optical Communications

Abstract

This paper reports a systematic approach for designing a low noise and low power optical receiver targeting high sensitivity imaging architectures for optical wireless communications. For line of sight tracking in optical wireless communications, a switching matrix is employed between the pixel/photodetector array and the transimpedance (TIA) amplifier. An optimization procedure is introduced to balance various performance parameters in the optical receiver front end when including the effect of the switch. The presented optical receiver consists of a low noise, wideband TIA, where noise and stability are optimized using a series inductor at the input. The TIA is followed by a limiter with offset cancellation and 50 Ω output buffer capable of 900 mV p-p differential output swing, over the 50 Ω resistance of the BERTScope. The receiver implemented in the IBM 130 nm CMOS technology, achieves a bit error rate of 10-12 at 5-Gb/s corresponding to 2.8 μA current at the input and at 4-Gb/s corresponding to 2.1 μA input current, in presence of 1 pF input capacitance representing the photodiode. The total power consumption including the on chip 50 Ω differential output buffer is 68 mW from 1.5 V DC supply. The die area including bonding pads and output buffer is 1106 μm × 895 μm.