Resolution tunable ring oscillator type TDC

This paper presents a high resolution tunable ring oscillator type TDC (Time to Digital Converter). The proposed structure uses 2 ring oscillators composed of 8 differential inverters. Can be activated by selecting one of the three resolution in the structure, and can be selected in a ratio of 15/16, 13/32, 63/64, depending on fast and slow of the differential inverter delay. Also to increase the total conversion range of the TDC, since when added to the MSB 1bit added only one D-FF(D flip-flop), has the advantage also in the power consumption and chip area. The resolution of TDC is 1.54ps, maximum range is 50.6ns when the differential inverter delay ratio is 31/32. This paper is based on 28nm CMOS process.