Multiphase technique to speed-up delay measurement via sub-sampling

A multi-phase technique for speeding up the measurement of delays via sub-sampling is presented. Measurement of delays using the sub-sampling approach leads to a very simple system implementation, and also provides the opportunity of trading off between bandwidth and accuracy. Such a scheme becomes extremely attractive for deep sub-micron processes due to its highly-digital nature and the ability to offer compact, low power, mixed-signal implementation alternatives. However, a drawback is the amount of averaging (measurement time) that is needed to get accurate results. A multiphase input clock scheme is proposed to address this issue, especially for the measurement of small delays, thereby speeding up the overall measurement. Simulation results from MATLAB Simulink confirm the speedup achieved upto a factor of eight with an eight-phase clock input for sufficiently small fixed test delays and also an improvement in SNR upto 11dB for slowly varying test delays.