Delay Interpolator Control for PVT-Stable Fine Delay Steps
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Solution Overview
Problem
Existing delay circuits face challenges in precisely controlling the ratio of coarse to fine delay steps due to process voltage temperature (PVT) variations, leading to conversion errors when switching between coarse and fine delay adjustments.
Innovation Solution
A delay interpolator system is introduced, comprising pull-up and pull-down devices controlled by separate control circuits, which receive delay codes to adjust the delay of signals, allowing for precise interpolation between coarse and fine delay steps, thereby tracking changes caused by PVT variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a delay circuit uses adjustable delay to center clock signal edges between data signal transitions, then timing alignment is improved, but conversion errors occur when switching between coarse and fine delay adjustments due to PVT variations
Solution Approach 1:
The delay circuit is segmented into coarse delay stages and fine delay stages, with the coarse delay providing bulk delay adjustment and the fine delay providing precise interpolation. This segmentation allows the circuit to achieve both large-range adjustability and fine precision while reducing conversion errors by treating coarse and fine delays as separate controllable entities.
Solution Approach 2:
The delay circuit employs dynamic control of delay elements based on PVT variations. The system continuously monitors and adjusts the delay parameters to track changes in process, voltage, and temperature conditions, ensuring that the timing alignment precision is maintained across varying operating conditions without introducing conversion errors.
2Measurement precision
If the delay circuit adjusts timing of clock signal relative to data signal, then timing alignment is improved, but the ratio of coarse to fine delay steps cannot be precisely controlled due to PVT variations
Solution Approach 1:
The delay circuit incorporates feedback mechanisms that monitor the actual delay achieved and compare it against the desired delay. Based on this feedback, the system dynamically adjusts the delay parameters to compensate for PVT variations, ensuring precise control over the ratio of coarse to fine delay steps while maintaining adaptability to changing operating conditions.
Solution Approach 2:
The circuit changes operating parameters such as voltage levels, transistor widths, or resistor values to dynamically adjust the delay characteristics. By modifying these parameters in response to PVT variations, the system maintains precise control over the coarse-to-fine delay ratio and adapts to different operating conditions without sacrificing timing alignment precision.
Data Source
AI summary
A delay interpolator includes pull-up devices, wherein each of the pull-up devices is coupled between a supply rail and a node, and pull-down devices, wherein each of the pull-down devices is coupled between the node and a ground. The delay interpolator also includes a first control circuit coupled to the pull-up devices, wherein the first control circuit has a first input configured to receive a first signal, a second input configured to receive a second signal that is delayed with respect to the first signal, and a control input configured to receive a first delay code; and. The delay interpolator further includes a second control circuit coupled to the pull-down devices, wherein the second control circuit has a first input configured to receive the first signal, a second input configured to receive the second signal, and a control input configured to receive a second delay code.