High Precision Digital Time Conversion Circuit

Digital to time converter(DTC)is a kind of digital signal control to achieve different input to output delay,can be used to adjust the propagation delay of critical signal path,using DTC can relatively improve the time resolution.In recent decades,DTC have received increasing attention from both academic and industrial research,and their main applications are in frequency synthesis and wired/wireless transmitters and receivers.DTC are similar to traditional digital-to-analog converters(DAC)in that important performance characteristics include dynamic range,resolution,accuracy,nonlinearity and monotonicity,but also power consumption and jitter or phase noise.This dissertation focuses on a wide dynamic range,high precision DTC circuit with the following main components.(1)The conventional DTC circuit structure is analyzed,and a three-stage DTC architecture is proposed with the goal of achieving wide dynamics and high-precision tuning,including three parts of coarse tuning based on delay-locked loop structure,middle tuning based on delay chain and fine tuning based on phase interpolator,which achieves the expected delay conversion effect.(2)In order to calibrate the DTC output delay variation due to process fluctuation,a new self-calibration method for digital time conversion circuit is proposed in the mid-tuning section.The calibration circuit adds capacitor arrays at each stage of the DTC delay unit for maximum delay calibration,converts the signal maximum output delay time to voltage through the time-voltage conversion circuit,and then amplifies the difference between the converted voltage and the calibration voltage,and the amplified result is compared by a comparator,and the comparison result is used to adjust the delay unit load capacitance size through the control circuit,so as to precisely adjust the maximum delay of the DTC.The adaptive calibration of the maximum output delay time of the DTC is realized.Based on the 40 nm CMOS process,the DTC was designed with a supply voltage of1 V and a reference frequency of 250 MHz simulation conditions,and the simulation shows that the design achieves a dynamic range of 0?4ns for the delay of the DTC with a minimum resolution of 3.188 ps.In the DTC calibration circuit,a calibration voltage of650 m V-860 m V was achieved in the range of 578 ps In the DTC calibration circuit,the maximum output delay calibration of the digital time converter was achieved in the calibration voltage range of 650 m V-860 m V with a calibration error of no more than1.25%.This paper focuses on the study and design of DTC circuits,which have received increasing attention from academic and industrial research in recent decades.DTC is a delay time controlled by a digital code on a reference input clock that allows dynamic modulation of the period of the DTC output signal.DTC is mainly used in frequency synthesis and wired/wireless transmitters and receivers,among other applications.Similar to conventional DAC,important performance characteristics include dynamic range,resolution,accuracy,nonlinearity and monotonicity,but also power consumption and jitter or phase noise.