Clock Skew Control Circuit Using Segmented Delay
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Solution Overview
Problem
Conventional clock systems for electrical devices face challenges in fine skew control, as existing methods either result in large and complex circuitry or are limited in their ability to perform precise skew adjustments, leading to issues with channel-to-channel skew and system delay variations.
Innovation Solution
The implementation of a clock skew control circuit with coarse and fine skew circuits, multiplexers, and memory for controlling clock signal delays, utilizing a bias signal and current-controlled digital-to-analog converters to provide precise and independent delay adjustments, allowing for fine-tuning of clock signals without increasing the number of stages in the VCO.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional VCO-based skew control methods are used to reduce large variations in skew, then coarse skew control is achieved, but fine variations in skew control cannot be performed and the circuit becomes large and complex if many stages are used
Solution Approach 1:
The skew control circuit is divided into two independent segments: a coarse skew control circuit that handles large variations using VCO stage clocks, and a fine skew control circuit that handles fine variations using programmable delay elements. This segmentation allows each segment to be optimized for its specific function without requiring the entire system to be overly complex, thereby achieving high precision skew control while managing circuit complexity.
2Measurement precision
If more stages are added to the VCO to achieve fine variations in skew control, then skew control precision improves, but the VCO slows down and additional jitter is created
Solution Approach 1:
The control function is segmented between coarse VCO-based control and fine programmable delay control. The fine skew control circuit uses programmable delay elements that do not require additional VCO stages, thus maintaining VCO speed while achieving fine skew control precision.
Solution Approach 2:
A programmable delay element acts as an intermediary between the VCO output and the final clock signal. This intermediary provides the fine adjustment capability without requiring modifications to the VCO itself, thereby preserving VCO speed characteristics while enabling precise skew control.
3Reliability
If gate delays and trimming are used to eliminate mismatch between clock channels, then some mismatch reduction is achieved, but only a very coarse approximation is obtained and overall mismatch is not reduced, especially over process, voltage and temperature
Solution Approach 1:
The skew control circuit transitions from static gate delays to dynamic programmable delay elements that can be adjusted in real-time. The delay values are stored in memory and can be programmed to compensate for process, voltage, and temperature variations, providing adaptive mismatch reduction that maintains clock channel matching under varying operating conditions.
Solution Approach 2:
The circuit changes the delay parameter dynamically using programmable delay elements controlled by digital values stored in memory. This allows precise adjustment of delay characteristics to compensate for PVT variations, achieving high precision mismatch reduction that static gate delays cannot provide.
Data Source
AI summary
Systems and methods are disclosed herein to provide improved clock, delay, and skew techniques. For example, in accordance with an embodiment of the present invention, an integrated circuit includes a clock generator to provide a bias signal and a clock signal, with control logic providing a delay control signal based on the bias signal and a multi-bit control signal. A clock skew circuit provides a delay to the clock signal based on the delay control signal provided by the control signal. Memory coupled to the control logic provides the multi-bit control signal.