Analysis of the transistor-related noise in integrated p-i-n-HBT optical receiver front-ends

The equivalent-input-noise-current spectral density for a monolithically integrated optical receiver front-end using InP/InGaAs heterojunction bipolar transistors and a p-i-n photodiode is computed from a small-signal model. Particular attention is paid to the contributions to the noise from the HBT in the first stage of the amplifier. It is shown that with transistors designed for 1-10-Gb/s receivers the base current shot noise dominates in the frequency range from 10 MHz to 1 GHz, and both the base resistance thermal noise and the collector current shot noise are important at higher frequencies. Device features which determine the extent of these noise sources are identified, and ways to improve the noise performance are discussed.<
>