Self-Calibrating Time-to-Digital Converter for Lidar
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Solution Overview
Problem
Conventional time-to-digital converters face challenges in maintaining calibration between consecutive events due to the rarity of stopping events, leading to measuring errors in applications like lidar systems.
Innovation Solution
A time-to-digital converter design featuring a self-calibrating chain of gate delay elements connected in parallel and series, with a charge-pump and phase-detector unit for feedback control, using a push-pull signal to maintain calibration independently of stopping events, and a specific configuration of time-delay elements and flip-flop units to enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional time-to-digital converters use stopping events for self-calibration, then calibration can be performed, but calibration is not retained between consecutive events leading to measuring errors
Solution Approach 1:
The patent implements a feedback mechanism where the output of the charge-pump and phase-detector unit is fed back to the input of the gate delay elements. This closed-loop feedback system continuously adjusts the delay elements to maintain calibration without requiring stopping events, thereby resolving the contradiction between measurement precision and calibration retention.
Solution Approach 2:
The system performs self-calibration continuously through the feedback loop, making the calibration process autonomous and independent of external stopping events. The charge-pump and phase-detector unit automatically adjusts the gate delay elements to maintain accurate time measurements, eliminating the need for manual intervention or event-based calibration.
2Measurement precision
If stopping events are used for calibration, then calibration can be achieved, but calibration is not maintained between rare events
Solution Approach 1:
The patent enables continuous calibration action through the feedback loop, which operates continuously rather than intermittently. The charge-pump and phase-detector unit continuously adjusts the gate delay elements to maintain calibration, eliminating the gaps between calibration events and ensuring constant measurement accuracy without waiting for rare stopping events.
3Measurement precision
If conventional calibration methods are used, then calibration can be performed at event stops, but measuring errors occur between events
Solution Approach 1:
The feedback loop continuously monitors and adjusts the gate delay elements, maintaining calibration stability between events. The charge-pump and phase-detector unit receives feedback signals and automatically corrects any drift, ensuring consistent measurement precision without the manufacturing precision issues that arise from event-based calibration.
Data Source
AI summary
A time-to-digital converter includes a self-calibrating, n-stage chain of a number n of gate delay elements connected in parallel and series between a clock signal line for supplying a clock signal and a stop signal line for supplying a stop signal; and a charge-pump and phase-detector unit for the feedback control of the gate delay elements, having a first input as a controlled-variable input, a second input as a reference-variable input, and an output as a correcting-variable output. The clock signal line is connected to the first input of the charge-pump and phase-detector unit, a push-pull line for supplying a push-pull signal is connected to the second input, and, for feedback, the gate delay elements are connected to the output of the charge-pump and phase-detector unit.