Injection-Locked Phase Rotator for Glitch-Free Clock Phase Shifts
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Solution Overview
Problem
Existing circuitry for phase shift control in oscillator-based clock generation systems faces challenges with noise, phase skew, and glitches, particularly at higher frequencies, which hinder data transfer accuracy and throughput.
Innovation Solution
Employing an injection-locked-oscillator-based phase rotator with a phase selector and control logic to asynchronously adjust phase shifts, preventing glitches and reducing phase skew by averaging phase delay skew to zero, using a phase rotator and control logic to adjust the phase of an injection-locked oscillator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional phase shift control circuitry is used in oscillator-based clock generation systems, then phase adjustment capability is provided, but noise, phase skew, and glitches occur particularly at higher frequencies
Solution Approach 1:
The patent introduces an injection-locked oscillator (ILO) as an intermediary component between the phase detector and the feedback clock signal generation. The ILO receives a clock signal from a digitally controlled oscillator (DCO) and generates an output clock signal with adjusted phase characteristics. This intermediary approach allows phase manipulation without directly modifying the feedback path, thereby reducing noise and phase skew while maintaining phase control capability
Solution Approach 2:
The patent replaces traditional mechanical or direct electronic phase shift control mechanisms with an injection-locked oscillator-based system. Instead of using conventional phase shifters that introduce noise and glitches, the invention uses the ILO's natural oscillation properties and injection locking mechanism to achieve phase control, substituting the problematic mechanical/electronic phase adjustment system with a more reliable oscillator-based approach
2Adaptability or versatility
If phase control circuitry is implemented to adjust phase at higher frequencies, then phase tuning capability is improved, but glitches and phase skew increase
Solution Approach 1:
The ILO serves as a mediator that receives the DCO clock signal and transforms it into an output signal with desired phase characteristics. By using the ILO as an intermediary, the system achieves phase tuning capability through the injection locking mechanism rather than through direct phase manipulation that causes glitches. The ILO's oscillation naturally smooths out phase transitions, reducing harmful phase skew and glitches while maintaining adaptability
Solution Approach 2:
The patent changes the operational parameters of the oscillator system by using injection locking instead of direct phase shifting. The ILO is driven by the DCO signal at a frequency that locks the ILO's oscillation, and by controlling the injection frequency and phase, the system achieves phase tuning without the harmful effects of traditional phase shifters. This parameter-based control approach maintains versatility while eliminating glitches and phase skew
3Measurement precision
If additional clock modification circuitry is added between phase detector and feedback clock signal generation, then phase control precision is improved, but device complexity increases
Solution Approach 1:
The injection-locked oscillator serves multiple functions simultaneously: it acts as a frequency divider, a phase shifter, and a signal cleaner. By using the ILO for these multiple purposes, the patent reduces the need for separate dedicated circuits for each function. The single ILO component provides phase control precision while avoiding the complexity of multiple separate modification circuits, as it universally handles frequency conversion, phase adjustment, and noise reduction
Solution Approach 2:
The patent merges the functions of frequency division, phase adjustment, and signal conditioning into a single injection-locked oscillator component. Instead of having separate circuits for each function between the phase detector and feedback clock generation, the ILO combines these operations in one integrated element. This merging approach maintains phase control precision while significantly reducing device complexity compared to using multiple separate modification circuits
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively minimizes glitches and phase skew in feedback clock signals, enhancing data transfer accuracy and throughput while reducing implementation costs and complexity.
Implementation Method 1
an injection-locked-oscillator-based phase rotator
Data Source
AI summary
A circuit includes a phase selector to generate an injection clock signal having an injection phase based on a phase of a digitally controlled oscillator clock signal generated within a phase-locking feedback loop. An injection-locked oscillator (ILO), coupled to an output of the phase selector, generates an ILO clock signal that is convertible to provide a feedback clock signal of the circuit. Logic, coupled between an output of the ILO and the phase selector, to, at each predetermined number of cycles of the DCO clock signal, cause the phase selector to output a phase shift in the injection clock signal that causes the ILO clock signal to comprise a rotated phase, relative to the injection phase, and that prevents a glitch in the injection clock signal.