A linear high gain time difference amplifier using feedback gain control

This paper describes a feedback time difference amplifier (FTDA) with good linearity and high gain for coarse-fine time-to-digital converters. The symmetrical FTDA has two identical output generators. Each one consists of one SR-latch, one XOR gate, one buffer and two feedback P-type keepers. The improvement in linearity and time difference gain is achieved with two feedback paths based on meta-stability of the SR-latch. Its validity was demonstrated using 130nm CMOS technology. The power consumption is 91.54uW for the highest gain at 2MHz input signals. The gain can be controlled from 25.06 to 734.9 with a ±20ps input time interval.