Cross-Coupled PLL Timing Platform for Low-Jitter Clock Synchronization
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Solution Overview
Problem
Existing clock synchronization circuits face challenges in efficiently generating multiple synchronized clock signals across networks due to high jitter and limited adaptability to varying timing applications.
Innovation Solution
A semiconductor device incorporating a combination of analog and digital phase-locked loops (APLL and DPLL) with fractional output dividers (FOD) and configurable cross-coupling networks, utilizing summation modules to dynamically adjust fractional frequency offset signals for precise clock synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If digital phase-locked loops are used instead of analog PLLs, then device area is reduced, but signal jitter increases
Solution Approach 1:
The patent combines digital phase-locked loops and analog phase-locked loops into a hybrid timing synchronization system. The DPLL provides compact size and programmability, while the APLL contributes low jitter performance through its analog voltage-controlled oscillator. The cross-coupling network integrates outputs from both loop types to achieve both area efficiency and signal quality.
Solution Approach 2:
The timing circuit employs a composite architecture combining digital and analog components. The digital portion (DPLL) handles frequency synthesis and programmability, while the analog portion (APLL) provides high-quality clock signals with low jitter. This composite approach leverages the strengths of both digital and analog domains to resolve the contradiction between area reduction and jitter performance.
2Device complexity
If fixed frequency division is used in clock synchronization, then circuit complexity is reduced, but adaptability to varying timing applications deteriorates
Solution Approach 1:
The patent implements dynamic frequency division through fractional output dividers that can be programmatically adjusted. The system allows real-time modification of division ratios to adapt to different timing requirements across multiple networks. This dynamic capability enables the same hardware to serve various synchronization applications without requiring fixed, application-specific circuit designs.
Solution Approach 2:
The timing synchronization circuit is designed as a universal platform capable of supporting multiple networks and various timing applications simultaneously. The cross-coupled architecture with programmable fractional dividers allows the system to adapt its output frequencies and phases to match different network requirements, making it versatile rather than application-specific.
3Reliability
If analog phase-locked loops are used for clock synchronization, then signal jitter is reduced, but device area increases
Solution Approach 1:
The patent segments the clock synchronization function into separate digital and analog modules. The DPLL handles frequency control and programmability in a compact digital format, while the APLL is dedicated solely to generating low-jitter clock signals. This segmentation allows each module to be optimized for its specific function, reducing the overall area compared to a full analog implementation while maintaining low jitter performance.
Data Source
AI summary
Apparatuses, devices, and systems for time synchronization are described. A timing circuit can include an analog phase lock loop (APLL), a plurality of digital phase lock loops (DPLLs) and a plurality of fractional output dividers (FODs). The timing circuit can receive the plurality of reference clock signals. The timing circuit can use the plurality of reference clock signals to generate at least one fractional frequency offset signal. The timing circuit can apply at least one operand on the at least one fractional frequency offset signal. The timing circuit can sum results of the application of the at least one operand on the at least one fractional frequency offset signal to generate a plurality of signals that control frequencies of a plurality of output clock signals that can be synchronized with the plurality of reference clock signals.