Clock Tree Idle-State Toggling for Symmetric Aging Control
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Solution Overview
Problem
Asymmetric aging in clock paths leads to duty-cycle distortion in clock signals, causing timing issues in circuits due to unequal stress on transistors during idle modes, resulting in duty-cycle shifts that can lead to setup and hold time violations.
Innovation Solution
A toggle circuit and multiplexer system that alternately parks the clock path input low and high in idle modes, balancing the aging of transistors to reduce duty-cycle distortion, by toggling the logic state of the clock path in response to the enable signal and selecting between clock signal passing and gating based on the enable signal's logic state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the clock path input is parked at a fixed logic state during idle modes, then the circuit operation is simplified, but asymmetric aging occurs causing duty-cycle distortion
Solution Approach 1:
The patent applies periodic action by alternating the parked logic state of the clock path input between idle modes. Instead of fixing the input at one state, the system periodically switches between logic 0 and logic 1 states across consecutive idle periods, ensuring that each state is applied for equal cumulative time. This periodic alternation balances the aging stress on transistors and prevents duty-cycle distortion while maintaining simplified circuit operation.
2Device complexity
If asymmetric aging is allowed to occur, then device complexity is reduced, but timing violations occur due to duty-cycle distortion
Solution Approach 1:
The invention uses periodic alternation of the clock path input state between idle modes to balance aging effects. By switching the parked state between logic 0 and logic 1 in a periodic manner, the system achieves symmetric aging compensation without requiring complex real-time monitoring or adjustment mechanisms. This approach maintains timing correctness while keeping the device complexity low.
3Reliability
If the clock signal is continuously passed without gating, then the clock path remains active and functional, but power consumption increases and asymmetric aging accelerates
Solution Approach 1:
The patent implements periodic gating of the clock signal during idle modes by alternating the parked state of the clock path input. The clock signal is gated (blocked) during each idle mode, and only passed during active modes. By periodically alternating the parked state between logic 0 and logic 1 across consecutive idle modes, the system reduces power consumption while preventing asymmetric aging through balanced stress application.
Data Source
AI summary
In certain aspects, an apparatus includes a gating circuit having an enable input, a signal input, and an output, wherein the enable input is configured to receive an enable signal. The apparatus also includes a toggle circuit having an output, wherein the toggle circuit is configured to toggle a logic state at the output of the toggle circuit based on the enable signal. The apparatus further includes a multiplexer having a first input, a second input, and an output, wherein the first input of the multiplexer is coupled to the output of the gating circuit, the second input of the multiplexer is coupled to the output of the toggle circuit. The multiplexer is configured to select one of the first input and the second input based on the enable signal, and couple the selected one of the first input and the second input to the output of the multiplexer.