Replica Delay Circuits for PVT-Matched Synchronous Timing
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Solution Overview
Problem
Synchronous circuits in high-speed digital designs face challenges in accurately matching propagation delays across variations in integrated circuit process, power supply voltage, and temperature, which affects timing margins and operating speed.
Innovation Solution
The implementation of delay circuits with a similar or identical architecture to synchronous circuits, using a replica design with a static logic value to enable the delay circuit, ensuring that the delay matches the propagation delay of the synchronous circuit, thereby maintaining timing margins across PVT variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If synchronous circuits are used in high-speed digital circuits, then operating speed is improved, but timing margins deteriorate due to propagation delay variations across PVT variations
Solution Approach 1:
The patent creates a replica synchronous circuit that copies the architecture and logic gates of the original synchronous circuit. This replica circuit is used to measure and match the propagation delays of the original circuit across PVT variations, enabling accurate delay compensation while maintaining high operating speeds.
2Reliability
If delay circuits are designed to match propagation delays across PVT variations, then timing margins are improved, but device complexity increases
Solution Approach 1:
Instead of using complex programmable circuitry or calibration mechanisms, the patent employs a simplified replica circuit that mirrors the basic architecture of the original synchronous circuit. This copying approach achieves accurate delay matching across PVT variations while minimizing additional device complexity.
3Measurement precision
If replica circuits are used for delay matching, then delay accuracy is improved, but manufacturing precision requirements increase
Solution Approach 1:
The replica synchronous circuit is designed to copy the exact logic gate structure and topology of the original circuit. Since both circuits are fabricated using the same process on the same chip, they experience identical PVT variations, which automatically compensates for manufacturing variations and maintains high delay matching accuracy without requiring ultra-precise manufacturing.
Data Source
AI summary
Delay circuits capable of providing delays closely matching propagation delays of synchronous circuits are described. In one design, an apparatus includes a synchronous circuit and a delay circuit. The synchronous circuit includes a forward path from a data input to a data output. The synchronous circuit receives input data and provides output data with a propagation delay. The delay circuit receives an input signal and provides a delayed input signal having a delay matching the propagation delay of the synchronous circuit. The delay circuit includes at least two logic gates in the forward path of the synchronous circuit. The synchronous and delay circuits may be implemented based on the same or similar circuit architecture. The delay circuit may be based on a replica of the synchronous circuit, with the replica having feedback loops broken and clock input coupled to appropriate logic value to always enable the delay circuit.