Time difference amplifiers to improve the dynamic range of MASH time encoded ADCs

This paper presents a time difference amplifier to improve the resolution of cascaded Time Encoded (TE) Analog-to-Digital Converters (ADCs). Time difference amplifiers are employed to increase the resolution of Time-to-Digital Converters, and most of them are based on imposing a certain time offset at the input of an SR latch. They are limited in their gain and input range, and exhibit a large delay. This paper proposes a novel analog time difference amplifier that can achieve a more accurate and higher gain with limited delay. These features make this circuit more suitable for multi-stage noise shaping (MASH) TE ADCs. The dynamic range extension is proven by time-domain simulations of a 1-1 TE ADC. The residue of the first stage is a pulsed signal, which pulse-width is extended by the time difference amplifier and applied into the second stage. This allows a dynamic range improvement of around 17dB for a gain of 7.