Clock Tree Variation Measurement and Compensation for IC Latency
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Solution Overview
Problem
Modern communication protocols require low and predictable latency in integrated circuits (ICs), which is compromised by clock tree variation due to voltage and temperature fluctuations, leading to the use of phase FIFO memories that increase latency and resource requirements.
Innovation Solution
A system for measuring and compensating for clock tree variation using a clock variation measurement controller (CVMC) that includes clock counter circuits, synchronizer circuits, and compensation circuits to adjust clock signals based on real-time measurements of voltage-temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phase FIFO memories are inserted to compensate for clock tree variation, then clock distribution reliability is improved, but device complexity and area increase
Solution Approach 1:
The patent implements a feedback mechanism where a measurement circuit continuously monitors clock tree variation and feeds this information to a compensation circuit. The compensation circuit dynamically adjusts clock signal parameters (phase, frequency, or delay) based on the measured variation, creating a closed-loop system that maintains reliable clock distribution without requiring large phase FIFO memories.
Solution Approach 2:
The patent changes the parameters of the clock signal itself (phase, frequency, or propagation delay) dynamically based on measured variation. Instead of using fixed-size phase FIFO memories, the system adjusts clock signal parameters in real-time to compensate for voltage and temperature variations, thereby reducing the need for large buffering structures.
2Reliability
If phase FIFO memories are inserted to compensate for clock tree variation, then clock distribution reliability is improved, but latency increases
Solution Approach 1:
The real-time feedback mechanism allows the system to detect and compensate for clock tree variation as it occurs, rather than buffering data for extended periods. This dynamic compensation reduces the buffering time required, thereby reducing latency while maintaining reliability.
Solution Approach 2:
By dynamically adjusting clock signal parameters (phase, frequency, delay) based on measured variation, the system compensates for timing issues without requiring large phase FIFO memories that would increase latency. The parameter adjustments enable timely compensation with minimal buffering.
3Measurement precision
If larger phase FIFO memories are used to compensate for VT variation, then measurement precision is improved, but area increases
Solution Approach 1:
The feedback-based measurement circuit continuously monitors clock tree variation with high precision and feeds this information to the compensation circuit. This real-time measurement approach achieves accurate VT variation compensation without requiring large phase FIFO memories, thereby reducing IC area while maintaining precision.
Solution Approach 2:
The patent replaces the mechanical/large-scale phase FIFO memory structure with an electronic measurement and compensation system. Instead of using large buffering structures to handle variation, the system uses electronic sensors and control circuits to detect and compensate for variation, significantly reducing the area required.
Data Source
AI summary
A system for clock variation measurement includes a first clock counter circuit configured to generate a plurality of first counts of a first clock signal, a second clock counter circuit configured to generate a plurality of second counts of a second clock signal, a first synchronizer circuit configured to synchronize the plurality of first counts according to a third clock signal, and a second synchronizer circuit configured to synchronize the plurality of second counts according to the third clock signal. The system includes a difference circuit configured to generate a plurality of differences from respective count pairs as synchronized. The system includes a variation circuit configured to generate a variation signal indicating an amount of variation between the first clock signal and the second clock signal based, at least in part, on the plurality of differences.