Method for correcting consistency of multiple TDC outputs

Abstract

The invention discloses a method for correcting the consistency of multiple TDC outputs. The method comprises the following steps: S1, performing linear fitting on a digital code output by each TDC togenerate a fitting straight line; S2, inputting two time windows for each TDC, calculating the slope K and the intercept B of the fitting straight line corresponding to each TDC according to the widths of the two time windows and the digital codes output by the TDC, and obtaining the slopes Ki and the intercept Bi of all TDCs; S3, taking modes for the slopes Ki and the intercept Bi of all TDCs toobtain Kref and Bref, and taking the Kref and the Bref as correction references; and S4, correcting the digital code output by each TDC according to the Kref and the Bref. According to the invention,linear fitting is carried out by calculating the digital codes output by different TDCs, the slope and intercept of a fitting straight line are calculated, statistics is carried out on the slope andintercept to obtain the mode of the slope and intercept, the mode is used as a calibration reference, and the digital codes output by each TDC are corrected according to the standard, so that the consistency of the output frequency of each TDC is ensured, and the influence of temperature, voltage and process environment is avoided.

Description

technical field [0001] The invention relates to the technical field of time-to-digital conversion, in particular to a method for correcting the output consistency of multiple TDCs. Background technique [0002] The principle of DTOF (Direct Time Of Flight) distance measurement is: the laser transmitter emits a laser signal to the object to be measured, and at the same time triggers the TDC (Time Digital Converter) to start timing. After the laser light is reflected by the surface of the object and received by the SPAD (Single Photon Avalanche Diode, single photon avalanche diode), the timing end signal of the TDC is triggered. TDC quantizes the time interval corresponding to the depth information into a digital signal output. [0003] Based on a SPAD array with tens of thousands of pixels, a large number of TDCs are required to work in parallel. In order to reduce the layout area and power consumption, the gated ring oscillator is widely used in the high-precision counting...

AI Technical Summary

Problems solved by technology

[0004] In view of the above problems, the purpose of the present invention is to provide a method for correcting the output consistency of multiple TDCs, so as to solve the problem that a large number of TDCs using ring oscillators have different frequencies under different temperature, voltage and process environments.

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