Time-to-Digital Converter Reset Timing to Eliminate Event Bias
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Solution Overview
Problem
Time-domain bias occurs in time-to-digital converters (TDCs) due to fixed measurement periods, leading to missed events, especially at high event frequencies, as they can only record one event per period, resulting in uneven event distribution and reduced recording accuracy.
Innovation Solution
Implementing an asynchronous reset mechanism using a delay line to uniformly distribute event latching across measurement periods by blocking the input stage for a time interval of independent duration, which can vary within a specified range, allowing for statistical distribution and reducing the likelihood of missing events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fixed measurement periods are used in TDC, then the converter can operate with simple timing control, but events occurring after the first event in each period are missed, causing time-domain bias
Solution Approach 1:
The patent applies dynamics by transitioning from fixed measurement periods to variable time intervals of independent duration. The time interval is dynamically adjusted based on when an event occurs within the measurement period, allowing the TDC to capture events uniformly across the entire period rather than being constrained to fixed windows. This resolves the contradiction by making the measurement mechanism adaptive rather than rigid.
Solution Approach 2:
The patent changes the parameter of measurement duration from fixed to variable. Instead of using a constant measurement period, the system uses time intervals of independent duration that can vary based on event timing. This parameter change allows the TDC to maintain simple control logic while eliminating time-domain bias, as the variable duration compensates for the position of events within the measurement period.
2Ease of operation
If the TDC records only the first event in each measurement period, then the converter maintains simple operation logic, but the number of recorded events decreases at high event frequencies
Solution Approach 1:
The system dynamically adjusts the measurement window based on event timing rather than using a fixed period. When events occur frequently, the variable time interval mechanism ensures that each event has an equal chance of being recorded, increasing the number of captured events while maintaining simple operation logic through the asynchronous reset mechanism.
Solution Approach 2:
The patent ensures continuous useful action by preventing the TDC from being blocked for extended periods. The time interval of independent duration is designed to be shorter than the measurement period, allowing the TDC to quickly recover and record subsequent events. This continuity mechanism increases productivity at high event frequencies while keeping the control logic simple.
3Reliability
If the input stage is blocked for extended periods after event registration, then the TDC ensures complete event capture, but the availability of the converter for new events is reduced
Solution Approach 1:
The patent changes the blocking duration parameter from extended to limited. The time interval of independent duration is specifically designed to be shorter than the measurement period, ensuring that the TDC recovers quickly and remains available for new events. This parameter optimization balances reliability by capturing events completely while maximizing productivity through sustained availability.
Solution Approach 2:
The system applies partial action by blocking the input stage for only the necessary time interval of independent duration rather than the entire measurement period. This partial blocking ensures complete event capture for the current event while allowing the TDC to quickly become available again for subsequent events, thus optimizing both reliability and productivity.
Data Source
AI summary
The method comprises providing a time-to-digital converter with a measurement period (3) for registration of events (1), and selecting time intervals of independent durations (4), each of the durations being independent of the registration of events. At each registration of an event, the time-to-digital converter is blocked from further registration for one of the time intervals of independent duration. Thus the recorded lengths of the time intervals (11, 13, 14, 16) corresponding to the occurrence of the events within each measurement period are uniformly distributed and a time-domain bias is avoided. The time-to-digital converter circuit includes a controlled gate for blocking the time-to-digital converter.