Ultra-low-noise and wideband-tuned optical receiver synthesis and design

Abstract

A new general optical receiver design method based on the synthesis of optimum noise-matching networks is presented. It is based on the noise figure concept in conjunction with broadband matching theory. The design is accurate because it directly utilizes the active device noise parameters, such as minimum noise figure, noise resistance, and optimum source impedance, which are readily available at microwave frequencies. The analysis has established the general noise-matching requirements of the tuning network that result in the minimum obtainable equivalent input noise current and the fundamental noise limit in tuned receivers. Synthesis procedures are described that can closely satisfy the general noise-matching requirements, which has led to a new low pass filter-type matching network with ultra-broadband characteristics that also approach the fundamental noise limit. The design principles are verified, with an experimental 10 Gb/s PIN-HEMT optical receiver that demonstrates a bandwidth of 6.3 GHz with a gain flatness of /spl plusmn/0.8 dB over the entire frequency range and a measured average noise current of 5 pA//spl radic/(Hz). >