Time-to-digital converter

Abstract

A time-to-digital converter (TDC) (300) is disclosed, which comprises a ring oscillator module (302) and a digital error correction module (304). The ring oscillator module is configured to receive asampling signal, an addressing signal, and a preset signal, and includes: a ring oscillator (3022) arranged with a plurality of inverters (3024); a phase sampler (3028) configured to sample phase signals generated by the inverters of the ring oscillator for generating a first output signal, on receipt of the sampling signal; a counter clock generator (3028) configured to generate first and secondclock signals, based on receipt of the sampling signal and respective phase signals generated by the first and last inverters of the ring oscillator; first and second counters (3030, 3032) configuredto respectively generate first and second counter output signals, based on receipt of the first and second clock signals respectively: and a data sampler (3034) configured to sample the first and second counter output signals to respectively generate second and third output signals. The digital error correction module is arranged to process the first, second and third output signals for generatinga digital signal representative of a time difference between receipt of a start signal and receipt of a stop signal by the TDC.

Description

technical field [0001] The present invention relates to a time-to-digital converter (time-to-digital converter, TDC). Background technique [0002] Time-to-digital converters (TDCs) have been used extensively for over 20 years in numerous applications requiring precise time interval measurements. Some examples of applications include particle and high energy physics, biomedical imaging such as positron emission tomography (PET), and various time-of-flight (ToF) measurements. With the development of complementary metal oxide semiconductor (CMOS) technology, the all-digital phase-locked loop (all-digital phase-locked loop, ADPLL) of the digital communication system also adopts TDC. By converting time or phase information into digital codes, TDC enables the evolution of PLLs to an all-digital domain, replacing traditional analog PLLs. Another emerging application area of ​​TDC is TDC-based analog-to-digital converter (analog-to-digital converter, ADC). Although requirements ...

AI Technical Summary

Problems solved by technology

However, the problem with the RO based TDC200 is that since the start and stop signals are not synchronized with the counter clock, the sampled counter output can be wrong

In addition, certain assumptions are made for the delay design of the RO-based TDC 200, which are difficult to meet in actual production

When process-voltage-temperature (PVT) variations and equipment mismatches occur, the actual delay time may be significantly different from the target delay time

Therefore, there is a high risk that the proposed error correction algorithm (for RO-based TDC 200) may not work as expected in a real manufacturing environment

In addition, the configuration of RO continuous free operation is likely to cause a large amount of power consumption

Also, the counter is always on, thus causing even more wasted power

Images