Frequency-Agile Clock Multiplier Using Parallel Injection-Locked Oscillators
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Solution Overview
Problem
Conventional phase-locked loop (PLL) multipliers incur long re-lock times and limited frequency agility, while injection-locked oscillators offer fast lock times but with a narrow input frequency range, making them unsuitable for frequency-agile systems that require low latency and wide frequency ranges.
Innovation Solution
A frequency-agile clock generator using multiple injection-locked oscillators with staggered lock ranges operates in parallel to achieve fast locking and a wide input frequency range, with a flexible-injection-rate oscillator that seamlessly transitions between different injection pulse rates to support broad frequency agility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional phase-locked loop (PLL) multipliers are used, then the system achieves stable frequency multiplication, but the re-lock time becomes long and frequency agility is limited
Solution Approach 1:
The patent divides the frequency multiplication function into multiple parallel injection-locked oscillators, each optimized for specific frequency ranges. This segmentation allows the system to switch between oscillators based on frequency requirements, achieving fast locking without sacrificing overall stability.
Solution Approach 2:
The system dynamically selects and switches between multiple injection-locked oscillators based on the desired output frequency. This dynamic adaptation enables fast frequency transitions by pre-positioning multiple oscillators with different lock ranges, eliminating the long re-lock time of conventional PLLs.
2Loss of time
If injection-locked oscillators are used, then the lock time becomes fast, but the input frequency range becomes narrow
Solution Approach 1:
The patent segments the overall frequency range into multiple sub-ranges, with each injection-locked oscillator optimized for a specific segment. This allows each oscillator to maintain fast locking characteristics while the collective system covers a broad input frequency range through parallel operation.
Solution Approach 2:
The system achieves multi-functionality by implementing multiple injection-locked oscillators that can be selectively activated. Each oscillator serves as a specialized frequency multiplier for its optimal range, and the system universally handles any frequency within the combined range by selecting the appropriate oscillator.
3Adaptability or versatility
If multiple injection-locked oscillators are operated in parallel, then the input frequency range and locking speed improve, but the area footprint increases
Solution Approach 1:
The patent merges multiple injection-locked oscillators into a unified frequency multiplication system with shared control and selection logic. This consolidation achieves broad frequency coverage and fast locking while minimizing the area footprint by sharing common circuitry among the parallel oscillators.
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 solution enables low-latency, frequency-agile clock multipliers with fast locking and a broad input frequency range, reducing power consumption and area footprint while maintaining small area requirements.
Implementation Method 1
injection-locked oscillators with staggered lock ranges operates in parallel to achieve fast locking and a wide input frequency range
Data Source
AI summary
In a first clock frequency multiplier, multiple injection-locked oscillators (ILOs) having spectrally-staggered lock ranges are operated in parallel to effect a collective input frequency range substantially wider than that of a solitary ILO. After each input frequency change, the ILO output clocks may be evaluated according to one or more qualifying criteria to select one of the ILOs as the final clock source. In a second clock frequency multiplier, a flexible-injection-rate injection-locked oscillator locks to super-harmonic, sub-harmonic or at-frequency injection pulses, seamlessly transitioning between the different injection pulse rates to enable a broad input frequency range. The frequency multiplication factor effected by the first and/or second clock frequency multipliers in response to an input clock is determined on the fly and then compared with a programmed (desired) multiplication factor to select between different frequency-divided instances of the frequency-multiplied clock.