Injection-Locked PLL with DLL Feedback for Low-Jitter Clocks
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Solution Overview
Problem
Conventional injection-locked phase-locked loops (IL-PLLs) suffer from static-phase-offset (SPO) mismatches, leading to significant deterministic jitter and are not suitable for high-speed, low-noise clock generation due to reference spurs caused by process-voltage-temperature (PVT) variations.
Innovation Solution
An injection-controlled-locked phase-locked loop (ICL-PLL) is introduced, which incorporates a delay-locked loop coupled with an injection-locked phase-locked loop, where the injection-locked oscillator is in a feedback loop path of the delay-locked loop, and an adjustable delay is used to self-adjust pulse injection, controlling the position of the pulse signal for the injection-locked oscillator, thereby mitigating SPO and jitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional injection-locked phase-locked loop (IL-PLL) is used, then the circuit structure is simple, but static-phase-offset (SPO) mismatches occur leading to significant deterministic jitter
Solution Approach 1:
A delay-locked loop (DLL) is introduced as an intermediary component between the reference signal source and the injection-locked oscillator. The DLL acts as a mediator that dynamically adjusts the phase of the reference signal before it is injected into the oscillator, thereby eliminating SPO mismatches and reducing deterministic jitter while maintaining overall system simplicity
Solution Approach 2:
The invention implements a feedback mechanism where the output of the injection-locked oscillator is fed back to the DLL. The DLL continuously monitors the phase relationship and automatically adjusts the reference signal phase to maintain optimal locking conditions, thereby eliminating SPO and reducing jitter through closed-loop control
2Device complexity
If an injection-locked phase-locked loop (IL-PLL) is used, then the circuit structure is simple, but reference spurs are generated due to PVT variations
Solution Approach 1:
The invention introduces dynamic phase adjustment capability through the DLL, which can continuously adapt to PVT variations. Instead of a fixed phase relationship, the system dynamically tracks and compensates for drift caused by process, voltage, and temperature changes, thereby eliminating reference spurs while keeping the circuit structure relatively simple
3Ease of operation
If pulse injection position is not controlled, then the circuit operation is simple, but static-phase-offset (SPO) mismatches lead to large deterministic jitter
Solution Approach 1:
The DLL is configured to automatically adjust the pulse injection position without requiring external control or manual calibration. The system self-corrects phase mismatches by continuously monitoring the oscillator output and autonomously adjusting the reference signal phase, thereby eliminating SPO and reducing jitter while maintaining ease of operation
Data Source
AI summary
An apparatus relates generally to an injection-controlled-locked phase-locked loop (“ICL-PLL”) is disclosed. In this apparatus, a delay-locked loop is coupled to an injection-locked phase-locked loop. An injection-locked oscillator of the injection-locked phase-locked loop is in a feedback loop path of the delay-locked loop.