Bipolar Time-to-Digital Converter Using a Differential Delay Line
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Solution Overview
Problem
Digital phase-locked loops (DPLLs) face challenges in minimizing power consumption and phase noise due to the need for time-to-digital converters (TDCs) to measure positive times, which introduces additional offset and increases power and noise penalties, while maintaining high resolution and linearity in time-to-digital mapping.
Innovation Solution
The implementation of a bipolar time measurement technique using a differential delay line and a digital controlled oscillator (DCO) to eliminate the need for TDC offset, allowing for coarse time quantization without additional multiplexers, thereby reducing phase noise and power consumption, and enabling precise clock signal generation and time difference measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a TDC offset is introduced to measure positive times, then the TDC can handle positive time measurements, but power consumption and phase noise increase
Solution Approach 1:
The patent inverts the conventional unipolar TDC approach by implementing a bipolar TDC that can measure both positive and negative time differences. This is achieved by using a differential delay line where edges can propagate in opposite directions, eliminating the need for TDC offset and reducing power consumption while maintaining measurement precision
Solution Approach 2:
The patent changes the measurement parameter from unipolar (positive time only) to bipolar (positive and negative time), allowing the TDC to measure time differences in both directions. This parameter change eliminates the need for offset compensation and reduces the power penalty associated with unipolar measurement architectures
2Measurement precision
If a TDC offset is introduced to measure positive times, then the TDC can handle positive time measurements, but phase noise increases
Solution Approach 1:
The patent inverts the conventional unipolar TDC approach by implementing a bipolar TDC that can measure both positive and negative time differences. This is achieved by using a differential delay line where edges can propagate in opposite directions, eliminating the need for TDC offset and reducing power consumption while maintaining measurement precision
Solution Approach 2:
The patent converts the potential harm of offset introduction into a benefit by using differential signaling. The differential delay line structure allows the system to exploit the offset for bipolar measurement capability while simultaneously canceling out the harmful phase noise effects through differential cancellation
3Reliability
If additional TDC offset is introduced, then the TDC can provide margin for MMD induced edge variation, but device complexity increases
Solution Approach 1:
The patent makes the delay line universal by enabling it to perform multiple functions: measuring positive time differences, measuring negative time differences, and providing inherent margin for MMD induced edge variation through its differential structure. This eliminates the need for separate offset compensation circuits, reducing device complexity while maintaining reliability
Data Source
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AI summary
A delay line operates to propagate a plurality of delay stages comprising a first delay element and a second delay element. A generator coupled to the delay line is configured to provide the start edge to the plurality of delay stages of the delay line as a function of a digital control oscillator (DCO) counter value generated by a DCO counter. A DCO calculation component is configured to facilitate a determination of propagation counts of the delay line as a function of DCO periods of a DCO.