Multi-Channel Clock Architecture Using Local Multipliers for Low Power Sync
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Solution Overview
Problem
High power consumption and synchronization challenges in clock generation for multi-channel high-speed devices, particularly in optical coherent modems, due to the need for precise alignment and low power usage across multiple channels.
Innovation Solution
A low power clock generation architecture that reduces the clock rate to FS/8 or lower frequencies, using multipliers to generate higher clocks and local phase locked loops to ensure synchronization, reducing power consumption and complexity by eliminating the need for extensive calibration and divider-based architectures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high frequency clocks are distributed to multiple channels, then channel synchronization is achieved, but power consumption increases
Solution Approach 1:
The clock generation function is segmented and distributed to each channel locally, rather than centrally generating and distributing high frequency clocks to all channels. Each channel has its own local clock generation circuit that multiplies the low frequency reference clock to generate the required high frequency operating clocks, eliminating the need for power-hungry high frequency clock distribution networks while maintaining synchronization.
Solution Approach 2:
The reference frequency parameter is changed from traditional high frequency (FS/2) to a lower frequency (FS/N where N≥8). This parameter change fundamentally reduces the power consumption of clock generation and distribution circuits, while local multipliers restore the required high frequency operation at each channel, achieving low power consumption without sacrificing channel synchronization.
2Device complexity
If high frequency clocks are generated centrally, then clock distribution is simplified, but device complexity increases due to calibration requirements
Solution Approach 1:
The clock generation task is segmented and performed independently at each channel location using local multipliers, rather than centrally generating and distributing clocks. This segmentation eliminates the need for complex calibration procedures to ensure channel-to-channel synchronization, as each channel independently generates its own clocks from the same low frequency reference, automatically ensuring synchronization without requiring elaborate realignment processes.
3Use of energy by moving object
If low frequency reference clock is used, then power consumption is reduced, but clock alignment precision becomes challenging
Solution Approach 1:
Phase locked loops are employed in the clock generation architecture to provide feedback control. The PLLs lock onto the low frequency reference clock and generate precisely aligned high frequency clocks through feedback mechanisms, ensuring deterministic clock alignment and phase coherence across all channels even though the reference frequency is low. This feedback control eliminates timing uncertainties and ensures precise clock alignment.
Data Source
AI summary
Described are apparatus and methods for low power clock generation in multi-channel high speed devices. In implementations, a multi-channel data processing device includes a low frequency clock generation and distribution circuit configured to generate and distribute a 1/N sampling frequency (FS)(FS/N) clock, wherein N is larger or equal to 8, and multiple data processing channels connected to the low frequency generation and distribution circuit. Each data processing channel including input ports associated with different operating frequency clocks, and a channel local clock generation circuit comprising multipliers associated with some of the input ports, each multiplier configured to multiply the FS/N frequency clock to locally generate an operating frequency clock associated with an input port of the input ports.