VLSI Clock Distribution Using Split Sub-Clocks to Limit Attenuation
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Solution Overview
Problem
High-frequency clock signals experience significant power attenuation during transmission in very-large-scale integration (VLSI) systems due to parasitic resistances and capacitances, making it challenging to maintain the minimum power threshold required for signal reconstruction, especially as channel length increases, and increasing driving power is not always sufficient.
Innovation Solution
The original master clock signal is split into multiple lower-frequency sub-clocks, which are transmitted across multiple channels, reducing power attenuation and allowing for reconstruction of the original clock signal at the receiver with potentially lower driving power, using methods such as ring-shift registers or frequency dividers and shift registers, and error correction techniques like time-calibration to address timing errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the frequency of master clock signals is increased to improve system performance, then system performance is improved, but power attenuation during transmission increases significantly
Solution Approach 1:
The master clock signal is divided into multiple lower-frequency sub-clock signals using a frequency divider. Each sub-clock signal operates at a reduced frequency (e.g., half the original frequency), which significantly reduces power attenuation during transmission through the distribution channel. The sub-clock signals are then recombined at the receiver to reconstruct the original high-frequency master clock signal, thus achieving high system performance while minimizing energy loss during transmission.
2Reliability
If driving power is increased to maintain minimum power threshold at the receiver, then signal reconstruction reliability is improved, but system power consumption increases
Solution Approach 1:
By segmenting the high-frequency master clock signal into multiple lower-frequency sub-clock signals, the power attenuation during transmission is reduced. This allows the sub-clock signals to be transmitted with lower driving power while still meeting the minimum power threshold at the receiver, thereby maintaining signal reconstruction reliability without increasing overall system power consumption.
Solution Approach 2:
The frequency parameter of the clock signal is changed from high frequency to lower frequency during transmission. This parameter change reduces the impact of parasitic resistances and capacitances, allowing the signal to be transmitted with lower driving power while maintaining adequate power levels at the receiver for reliable reconstruction.
3Area of stationary object
If channel length is increased to distribute clock signals across more components, then system coverage is improved, but parasitic resistances and capacitances increase
Solution Approach 1:
The master clock signal is divided into multiple sub-clock signals that can be distributed through multiple channels simultaneously. This segmentation allows the system to cover a larger area by utilizing multiple distribution paths, while each individual channel operates at lower frequency with reduced parasitic effects, maintaining signal integrity across extended system coverage.
4Device complexity
If single distribution channel is used to simplify system structure, then device complexity is reduced, but power attenuation increases
Solution Approach 1:
The clock distribution system is segmented into multiple parallel channels, each transmitting a lower-frequency sub-clock signal. This segmentation reduces power attenuation in each individual channel compared to a single high-frequency channel. While the overall system complexity increases due to multiple channels, the trade-off is justified by the significant reduction in power attenuation and improved signal integrity.
Data Source
AI summary
In accordance with some embodiments, a method for high frequency clock distribution in a VLSI system includes splitting an original master clock signal into one or more pairs of lower-frequency sub-clocks for a destination in the VLSI system, distributing each lower-frequency sub-clock of the one or more pairs of lower-frequency sub-clocks to a corresponding channel coupled to the destination, and reconstructing a reference master clock signal at the destination from the one or more pairs of lower-frequency sub-clocks, wherein the reconstructed reference master clock signal replicates the original master clock signal.