Apparatus and method for adaptively adjusting amplifier gain based on detected distance to a target in a light detection and ranging (LiDAR) system. In some embodiments, the amplifier amplifies detected pulses obtained from a photodetector, and the gain is adjusted from among at least two selectable gain modes responsive to a measured time of flight (ToF) for the pulses. A first range of gain levels can be used for targets that are within a first maximum distance range, and a second range of gain levels can be used for targets that are beyond the first maximum distance range. Each mode can extend from a minimum to a maximum value along a selected linear slope. A gain adjustment circuit can use a Gilbert Cell or a multiplier and fully differential amplifier arrangement.