Burst-mode optical receiver with feed-forward dc-bias acquisition and flash-oversampling clock recovery

Abstract

An optical receiver receives a photocurrent from a photosensor and uses a transimpedance element to convert the photocurrent into an input signal. Next, an amplifier amplifies the input signal to produce an amplified input signal. At the same time, a clock-recovery circuit generates a clock signal, which is used to clock the amplified input signal to produce a receiver output. During an initial-calibration operation, the clock-recovery circuit phase-aligns a locally generated reference signal with transitions in the amplified input voltage signal to produce the clock signal by: feeding the reference signal through a delay-locked loop to produce a set of equally spaced phases; using the set of equally spaced phases to sample a preamble in the amplified input voltage signal to detect a crossing point; choosing a corresponding phase from the set of equally spaced phases based on the crossing point; and using the chosen phase to produce the clock signal.