Phase Interpolator Circuit for Precise Clock Edge Alignment
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Solution Overview
Problem
As clock signal frequency and data rate increase, the sampling window decreases, making it challenging to accurately align the rising and falling edges of the clock signal with the sampling window in digital periodic clock signals used in integrated circuits.
Innovation Solution
A phase interpolator circuit is developed, comprising low pass filter circuits and a multiplier circuit, which generates a phase shift in a varying signal by adjusting the common mode voltage and capacitance to align the clock signal edges within the sampling window, allowing for precise sampling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If clock signal frequency and data rate increase, then productivity is improved, but sampling window decreases making timing alignment more difficult
Solution Approach 1:
The patent implements dynamic phase adjustment by making the phase shift amount variable based on detected timing errors. The phase interpolator continuously adapts the clock signal phase to maintain optimal alignment with the sampling window, allowing the system to handle high data rates while preserving sampling accuracy through real-time dynamic control.
Solution Approach 2:
The patent employs a feedback mechanism where the sampling timing is monitored and phase adjustment control signals are generated based on detected timing deviations. This closed-loop feedback system automatically adjusts the phase interpolator to correct timing misalignment, enabling maintained sampling precision even as data rates increase and sampling windows shrink.
2Adaptability or versatility
If phase adjustment range is increased to cover 0-360 degrees, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent segments the full 360-degree phase adjustment range into multiple discrete phase shift steps. By dividing the continuous phase adjustment into quantized levels, the implementation can cover the complete phase range while using manageable circuitry for each discrete step, avoiding the need for complex continuous control mechanisms.
Solution Approach 2:
The patent changes the phase shift parameter in discrete increments across the 0-360 degree range. By implementing phase adjustment as a parameter that can be stepped through multiple values rather than continuously varied, the system achieves full phase coverage using simpler digital control logic and phase interpolator structures.
Data Source
AI summary
A phase interpolator circuit includes first and second low pass filter circuits and a multiplier circuit. The first low pass filter circuit increases a common mode voltage of a clock signal to generate a first varying signal. The second low pass filter circuit increases a common mode voltage of a clock signal to generate a second varying signal. The first low pass filter circuit can include a first variable capacitance, and the second low pass filter circuit can include a second variable capacitance. The multiplier circuit has a first input coupled to the first low pass filter circuit and a second input coupled to the second low pass filter circuit. The multiplier circuit generates a third varying signal in response to the first and the second varying signals. The phase interpolator circuit generates a phase shift in the third varying signal.