Digitally Controlled Delay Line With Calibrated Delta Delay Stages
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Solution Overview
Problem
Current precision timing systems in integrated circuit components face limitations in achieving high-resolution delay control, particularly due to quantization errors and linearity errors as signaling rates increase and data-eye timing budgets shrink, especially in hybrid delay lines with absolute delay stages.
Innovation Solution
The implementation of high-resolution digitally controlled delay lines (HR DCDLs) with delta delay stages, which include two digitally selectable signal paths with bias-controlled propagation times, coupled with absolute delay stages, allows for a hybrid delay line that extends the delay range beyond individual paths, using binary-weighted and power-of-two subdivisions to achieve precise delay control through calibration of delta delays as a fraction of absolute delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If hybrid delay lines with absolute delay stages are used, then delay range is extended, but quantization errors and linearity errors increase
Solution Approach 1:
The delay line is segmented into multiple stages with different delay ranges. Absolute delay stages provide coarse delay adjustment with large step sizes to extend the overall delay range, while delta delay stages provide fine delay adjustment with small step sizes to maintain timing precision. This segmentation allows the system to achieve both extended delay range and high timing precision simultaneously.
Solution Approach 2:
Different stages of the delay line have different local characteristics optimized for their specific functions. Absolute delay stages have larger delay steps suitable for extending the delay range, while delta delay stages have smaller delay steps suitable for precise timing control. This local quality differentiation allows each stage to operate optimally within its designated delay range.
2Productivity
If signaling rate is increased, then productivity is improved, but timing precision deteriorates due to reduced data-eye timing budget
Solution Approach 1:
The delay line employs digitally controllable delay stages that can dynamically adjust their delay values based on timing requirements. This dynamic control allows the system to maintain precise timing alignment even at high signaling rates where the timing budget is reduced, as the delay stages can be quickly reconfigured to compensate for timing variations.
Solution Approach 2:
The delay line incorporates feedback mechanisms that monitor timing alignment and adjust delay values accordingly. This feedback control enables the system to maintain timing precision at high signaling rates by continuously correcting for timing deviations, ensuring that strobe and data signals remain properly aligned despite the reduced timing budget.
3Length of moving object
If more delay stages are added to extend delay range, then device complexity increases
Solution Approach 1:
The delay line is segmented into a hierarchical structure with absolute delay stages providing coarse adjustment and delta delay stages providing fine adjustment. This segmentation allows the system to achieve extended delay range without requiring an excessive number of delay stages, as each stage operates within an optimized delay range rather than requiring one stage to cover the entire range.
Solution Approach 2:
The delay line merges absolute delay stages and delta delay stages into a unified hybrid structure. This combination allows the system to achieve extended delay range while maintaining manageable complexity, as the two types of stages work together synergistically rather than requiring separate independent delay lines.
Data Source
AI summary
In a delay control circuit having a plurality of series-coupled delay stages, an input signal is routed through one of the series-coupled delay stages via a first delay element if a first delay control value is in a first state, the first delay element imposing a first signal propagation delay according to a first bias signal. If the delay control value is in a second state, the input signal is routed through the one of the series-coupled delay stages via a second delay element instead of the first delay element, the second delay element imposing a second signal propagation delay according to a second bias signal. The first and second bias signals are calibrated such that the second signal propagation delay exceeds the first propagation delay by a predetermined time interval that is substantially briefer than the first signal propagation delay.