A Time-to-Digital Converter-based Correction Method for Charge Measurement through Area Integration

TL;DR

This paper presents a correction method using a time-to-digital converter to enhance charge measurement accuracy in digital signal processing, achieving nearly double the resolution through FPGA implementation and testing.

Contribution

It introduces a novel TDC-based correction algorithm for charge measurement, significantly improving resolution in digital charge measurement systems.

Findings

Charge measurement resolution improved from 0.231% to 0.126%.

Method successfully implemented on FPGA with high sampling rate.

Effective correction reduces measurement error due to waveform sampling uncertainty.

Abstract

A high-precision charge measurement can be achieved by the area integration of a digitized quasi-Gaussian signal after the signal passes through the shaper and analog-to-digital converter (ADC). The charge measurement contains an error due to the uncertainty of the first sampled point of a signal waveform. To reduce the error, we employ a time-to-digital converter (TDC) to measure the uncertainty precisely, and we design correction algorithms to improve the resolution of the charge measurement. This work includes analysis and simulations of the proposed algorithms and implementation of them in an FPGA device. Besides, the tests are also conducted to evaluate the performance of the correction method. Test results indicate that the resolution of the charge measurement is successfully improved from 0.231% to 0.126% by using a signal from the shaping circuit (with the amplitude of 2 V, and leading and trailing edges of about 80 ns and 280 ns, respectively) digitized at the sampling rate of 62.5 Msps.