Time difference amplifier using closed-loop gain control

Abstract

This paper demonstrates a TDA, whose input time difference is amplified into the output time difference. Cross coupled chains of variable delay cells with the same number of stages are applicable for TDA, and the gain is adjusted via DLL-like closed-loop control. The TDA was fabricated using 65nm CMOS and the measurement results shows that the time difference gain is 4.78 at a nominal power supply while the designed gain is 4.0. The gain is stable enough to be less than 1.4% gain shift under ± 10% power supply voltage fluctuation.