Electronic gain control with constant propagation delay for integrated transimpedance preamplifiers

This paper presents an electronic gain control scheme which significantly increases the dynamic range of an optoelectronic receiver without deteriorating the noise properties or affecting the propagation delay or bandwidth. A current buffer with variable attenuation is placed between the photodetector and the transimpedance preamplifier. The simulated dynamic range of the proposed front-end is 80 dB. A test circuit was designed for a pulsed time-of-flight laser rangefinder to verify the feasibility of the scheme. According to measurement results, the timing point varies ±5 ps when the gain is varied 24 dB (1:15)