Gated Ring Oscillator TDC Calibration for Nonlinear Timing Error
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Solution Overview
Problem
Gated ring oscillator (GRO) based time-to-digital converters (TDCs) experience non-linearities in measurement results due to varying response times caused by pulse-like current draw, leading to increased errors over measurement time.
Innovation Solution
A system comprising a GRO based TDC and a processor that determines a non-linearity model by measuring calibration signals, identifying variance from a target value, and applying corrections to measurement results to mitigate non-linearities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a GRO based TDC is used to measure time, then a large conversion range can be achieved, but non-linearities in measurement results occur due to varying response times
Solution Approach 1:
The patent applies preliminary action by performing calibration measurements before actual time measurements. The system measures calibration signals with known time intervals to determine non-linearity characteristics in advance, then uses these pre-determined characteristics to correct subsequent measurement results, thereby improving measurement accuracy while maintaining the large conversion range of the GRO based TDC
Solution Approach 2:
The patent implements feedback by using the measured non-linearity characteristics to correct measurement results. The system continuously monitors the relationship between measurement results and actual time intervals, determines non-linearity parameters, and applies corrections based on these parameters to compensate for the varying response times of the GRO, thus resolving the accuracy issue while preserving the adaptability benefit
2Measurement precision
If calibration signals are measured to determine non-linearity model, then measurement accuracy improves, but additional time and processing is required
Solution Approach 1:
The patent applies partial action by performing calibration with a limited set of calibration signals covering the measurement range, rather than exhaustive calibration at every possible time interval. The system determines non-linearity characteristics using these partial calibration measurements and applies them to correct the entire measurement range, thus improving accuracy while minimizing the time loss associated with calibration
Data Source
AI summary
Aspects of the disclosure provide for an apparatus comprising a time-to-digital converter (TDC) and a processor coupled to the TDC. In some examples, the TDC may be configured to receive a signal and generate a measurement result indicating a time between start and stop events of the signal. The processor may be configured to receive the measurement result, compare the measurement result to a target value, and determine a non-linearity model configured to correct a variance of the measurement result from the target value.