Optical receiver bandwidth enhancement using bootstrap transimpedance amplification technique

Abstract

Optical wireless link operates in high noise environments owing to ambient conditions such as sun for outdoors and fluorescent for indoors. The performance of free-space optics is subjected to several atmospheric factors like environmental temperature, fog, smoke, haze and rain. Signal-to-noise ratio (SNR) can vary significantly with the distance and ambient noise. Limited range due to ambient noise is the dominant noise. A good sensitivity and a broad bandwidth will invariably use a small area photodiode where the aperture is small. However, freespace optics requires a large aperture and thus, the receiver is required to have a large collection area, which may be achieved by using a large area photodetector and large filter. However, large area of photodetector produces a high input capacitance that will be reduced the bandwidth. Typical large photodetection area commercial detectors has capacitance are around 100-300pF compared to 50pF in fiber link. Hence, techniques to reduce the effective detector capacitance are required in order to achieve a low noise and wide bandwidth design. In this project, modeling and analysis the bootstrap transimpedance amplifier (BTA) of front-end receiver for input capacitance reduction has been simulated. This technique improved the conventional transimpedance amplifier (TIA) bandwidth up to 1000 times with an effective capacitance reduction technique for optical wireless detector