Clock Source Multiplexing to Prevent Aging-Induced Duty-Cycle Distortion
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Solution Overview
Problem
Asymmetric aging in clock paths causes duty-cycle distortion in clock signals, leading to timing issues in circuits due to bias temperature instability, which existing technologies have not adequately addressed.
Innovation Solution
A system that includes a gating circuit, a delay circuit, and a control circuit to manage clock signals, using a slow clock signal in idle mode to balance device aging and a glitch-mitigation circuit to ensure the width of high pulses meets a minimum pulse width, preventing timing issues during mode transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a clock signal is continuously distributed through the clock path, then the circuits can maintain normal timing operations, but asymmetric aging causes duty-cycle distortion that leads to timing violations
Solution Approach 1:
The patent applies periodic action by introducing a slow clock signal that periodically toggles the clock path input during idle mode. This periodic toggling balances the aging effects on different transistors in the clock path, preventing asymmetric aging and duty-cycle distortion while maintaining timing reliability when the fast clock signal is restored.
Solution Approach 2:
The patent implements preliminary action by applying a slow clock signal during idle mode before returning to fast clock operation. This preliminary action pre-balances the aging effects on clock path transistors, ensuring that when the fast clock signal is restored, duty-cycle accuracy is maintained and timing violations are prevented.
2Loss of energy
If the clock path input is parked at a fixed logic level during idle mode, then power consumption is reduced, but this causes asymmetric aging of transistors leading to duty-cycle distortion
Solution Approach 1:
Instead of parking the clock path input at a fixed logic level, the patent uses periodic action by applying a slow clock signal that toggles between logic levels during idle mode. This periodic toggling ensures both transistors in the clock path experience similar aging conditions, maintaining duty-cycle precision while keeping power consumption low compared to continuous fast clock operation.
3Manufacturing precision
If a slow clock signal is used during idle mode to balance aging, then duty-cycle distortion is mitigated, but glitches may occur during mode transitions that cause timing issues
Solution Approach 1:
The patent applies preliminary anti-action by detecting mode transitions between slow and fast clock signals and preemptively gating the slow clock signal to prevent glitches. The control circuit monitors the enable signal transitions and blocks the slow clock signal during the transition period, eliminating harmful glitches before they can cause timing violations.
Solution Approach 2:
The patent implements feedback by using the enable signal as a feedback mechanism to control the gating of the slow clock signal. The control circuit continuously monitors the enable signal state and adjusts the gating of the slow clock signal accordingly, preventing glitches during mode transitions while maintaining duty-cycle precision during idle mode.
4Device complexity
If the slow clock signal is not gated during mode transition, then the transition is simple, but narrow high pulses (glitches) are generated that cause timing violations
Solution Approach 1:
The patent applies preliminary anti-action by detecting mode transitions via the enable signal and preemptively gating the slow clock signal to prevent narrow high pulses. This simple gating mechanism, controlled by the enable signal transition, eliminates glitches without requiring complex control circuitry, maintaining timing reliability while keeping device complexity low.
Data Source
AI summary
In certain aspects, an apparatus includes a first gating circuit having an input and an output, wherein the input of the first gating circuit is configured to receive a first clock signal. The apparatus also includes a delay circuit having an input and an output, wherein the input of the delay circuit is coupled to the output of the first gating circuit. The apparatus further includes a control circuit configured to receive an enable signal, detect a logic state at the output of the delay circuit, and cause the first gating circuit to pass or gate the first clock signal based on the enable signal and the detected logic state at the output of the delay circuit.