Injection-Locked Oscillator Tuning for Low-Jitter Clock Stability
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Solution Overview
Problem
Electronic circuits, such as those in mobile devices, face challenges in maintaining operation across varying supply voltages and temperatures, leading to changes in electrical characteristics and behavior, necessitating designs that can operate with sufficient margins across manufactured variation spaces.
Innovation Solution
The implementation of injection-locked oscillator (ILO) circuitry that adjusts delay elements to match the natural oscillation frequency with the reference clock frequency, minimizing jitter and enhancing tolerance to voltage and temperature drift, using circuitry that determines settings by sampling output signals and adjusting delay elements based on relative measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ILO operates without frequency adjustment, then the circuit complexity is reduced, but the output jitter increases and tolerance to voltage and temperature drift decreases
Solution Approach 1:
The patent implements a feedback mechanism where the ILO output frequency is continuously measured and compared against the reference clock frequency. Based on this comparison, control signals adjust the delay elements in real-time to maintain frequency alignment, thereby improving tolerance to voltage and temperature drift while managing circuit complexity through intelligent control.
Solution Approach 2:
The patent dynamically changes the delay parameter of the ILO based on measured frequency deviations. By adjusting the delay element values in response to operating conditions (voltage and temperature variations), the system maintains optimal performance without requiring a completely complex redesign of the oscillator architecture.
2Reliability
If delay elements are adjusted to match frequencies, then output jitter is minimized, but the measurement and control complexity increases
Solution Approach 1:
The patent replaces complex mechanical frequency adjustment mechanisms with electronic delay elements that can be programmatically controlled. This substitution allows for precise frequency matching through digital or analog delay adjustment, reducing output jitter while avoiding the complexity of mechanical tuning systems.
Solution Approach 2:
The ILO system performs self-adjustment by automatically measuring its own output frequency and correcting deviations through feedback control. This self-service capability minimizes output jitter without requiring external complex measurement and control infrastructure, as the system monitors and corrects itself autonomously.
Data Source
AI summary
Embodiments of an integrated circuit (IC) comprising circuitry to determine settings for an injection-locked oscillator (ILO) are described. In some embodiments, an injection signal is generated based on a first clock edge of a reference clock signal, and is injected into an ILO. Next, one or more output signals of the ILO are sampled based on a second clock edge of the reference clock signal, and settings for the ILO are determined based on the samples. In some embodiments, a sequence of two or more time-to-digital (TDC) codes is generated based on a reference clock signal and a free-running ILO. In some embodiments, the TDC circuitry that is already present in a delay-locked loop is reused for determining the sequence of two or more TDC codes. The ILO settings can then be determined based on the sequence of two or more TDC codes.