A 22-bit 110ps time-interpolated Time-to-Digital Converter

This paper presents a 22-bit time-interpolated Time-to-Digital Converter (TDC) with 110ps temporal resolution for biochemical sensing applications, which utilize time-resolve luminescence imaging technique. The TDC achieves wide dynamic range operation by incorporating a hybrid architecture that combines a 14-bit digital counter based coarse TDC and an 8-bit Voltage-Controlled Delay Line (VCDL) based fine TDC. We have proposed and implemented a novel readout algorithm for VCDL operation that achieves high throughput temporal measurement. A prototype chip has been fabricated in a 65nm standard CMOS process and it consumes 2.4mA power from a 1.2V supply. The measurement results on the fabricated TDC demonstrates a Differential Nonlinearity (DNL) of 0.49LSB and an Integral Nonlinearity (INL) or 1.67LSB (1LSB=110ps). The implemented TDC architecture and its fast readout circuit can be readily used in a variety of time-resolved biomedical sensing or high-speed imaging applications that require both wide dynamic range performance and high frame rate implementations.