Design Of Full Digital Quantization System Based On TDC

The analog signal is converted into digital signal by sampling?quantification and coding,where quantization is the most critical step.With the development of CMOS technology,using digital circuits quantifies analog signal is a way which achieving large-scale mixed-signal systems,and it is also a common research hotspot in academia and industry.To quantify the analog signal,the amplitude and corresponding time information of the signal must be obtained.In today's processes,the time resolution of the circuit to the signal is better than the voltage resolution.Based on this characteristic,the amplitude of the signal can be first converted to a corresponding time interval,and then the time interval is accurately quantized.This method enables the quantization of analog signals with digital circuits.Time-to-Digital Converter(TDC)has high-precision time quantization characteristics.This paper studies the all-digital method based on TDC,which includes amplitude quantization and time quantization.This article designs related circuits based on standard CMOS processes.Through the work of this paper,we can lay the foundation for the digital quantization of analog signals.In amplitude quantization,the comparator is the key circuit that produces digital pulses for TDC measurements.In this paper,a digital discrete threshold comparator is designed.The threshold voltage of the comparator is controlled by a 7-bit digital code,which has the advantages of simple structure,small area and low power consumption.The comparator was fabricated by using the TSMC?0.18?m process.The test results show that the threshold voltage of the comparator can reach 1 m V within the adjustment range of 261?1479 m V,and the transmission delay is less than 1 ns.Time quantization is implemented using an all-digital TDC to measure the pulse width.In order to achieve wide dynamic range measurement,the all-digital TDC uses the time interpolation principle to divide the quantization interval into a coarse quantization interval and a fine quantization interval.The coarse quantization interval is quantized using a counter type TDC to obtain a wide dynamic range.The fine quantization interval is quantized using a delay chain TDC to obtain high temporal resolution.The all-digital TDC designed in this paper is also used in the TSMC?0.18?m process.The test results show that the measurement accuracy of the TDC chip is better than 300 ps,and the dynamic range is about 2.56 ?s.