Distributed VCO Clock Distribution via Transmission Line
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Solution Overview
Problem
In high-speed coherent optical communication systems, distributing a clock signal across multiple circuits or devices is challenging due to power consumption and jitter issues, especially at frequencies above 50-60 gigabaud per second, where conventional ring oscillators are inefficient and add significant power and noise.
Innovation Solution
A distributed voltage-controlled oscillator (VCO) system is implemented using LC tanks connected via a low resistance coaxial line, minimizing the need for buffers and reducing power consumption while maintaining low jitter, by synchronizing VCOs through a low loss transmission line that ties together internal switching nodes of multiple VCOs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional ring oscillators are used for clock distribution in high-speed coherent optical communication systems, then the system can operate at frequencies above 50-60 gigabaud per second, but power consumption increases significantly and jitter is added to the signal
Solution Approach 1:
Multiple VCOs are merged into a distributed configuration where their LC tanks are connected through a transmission line, forming a synchronized clock distribution system that shares the oscillation function across multiple devices rather than using separate ring oscillators in each circuit
Solution Approach 2:
A transmission line acts as an intermediary element connecting the LC tanks of multiple VCOs, enabling synchronized operation without requiring high-power buffer amplifiers, thus reducing overall power consumption while maintaining high-speed operation
2Ease of operation
If conventional ring oscillators are used for clock distribution, then the system can provide timing signals to multiple circuits, but jitter is significantly added to the clock signal
Solution Approach 1:
Multiple VCOs are combined in a distributed architecture where they share a common transmission line connection, allowing clock distribution to multiple circuits while the distributed nature of the system inherently reduces jitter accumulation compared to cascaded buffer approaches
Solution Approach 2:
The system uses voltage-controlled oscillators that can dynamically adjust their frequency based on control voltages applied to their respective LC tanks, enabling precise timing synchronization across distributed circuits while maintaining low jitter through controlled oscillation rather than buffered signal propagation
3Ease of operation
If buffers are used to distribute clock signals from a single VCO, then the clock can be distributed to multiple circuits, but power consumption increases and the system becomes more complex
Solution Approach 1:
The clock distribution function is segmented across multiple independent VCOs rather than using a single VCO with multiple buffers, where each VCO independently generates and distributes its clock signal through the transmission line, simplifying the overall system architecture by eliminating the need for complex buffer trees
Solution Approach 2:
Each VCO in the distributed system serves multiple functions: generating its own clock signal, distributing it through the transmission line to multiple circuits, and being controllable through voltage inputs, replacing the need for separate buffer amplifiers and reducing system complexity
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 approach enables efficient distribution of a clock signal with minimal power consumption and reduced jitter, effectively supporting high-speed conversions without the need for multiple buffers, thereby improving the accuracy and reliability of signal conversions in optical communication systems.
Implementation Method 1
each VCO of the set of VCOs are connected via a transmission line
Implementation Method 2
each VCO of the set of VCOs has an LC tank
Data Source
AI summary
In a first and second embodiment, an apparatus and system comprising a set of voltage controlled oscillators (VCOs); wherein each VCO of the set of VCOs has an LC tank; wherein each VCO of the set of VCOs is connected via a transmission line. In a third embodiment, a method comprising connecting each VCO in a set of VCOs by connecting each respective LC tank of each VCO of the set of VCOs with a transmission line.