SoC Isolation Wrapper for Low-Power Standby Signal Routing
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Solution Overview
Problem
Existing SoC designs face challenges in efficiently routing isolation signals between AON domains, especially when these domains are far apart, as traditional solutions require significant area and are prone to noise and power loss during low power modes.
Innovation Solution
The implementation of a voltage level detector powered by either a switchable or AON power supply to generate isolation signals, combined with an ISO wrapper circuit that includes a pass-through latch controlled by the voltage level detector, allows for clean isolation signals to be routed without additional buffering, even when switchable domains are powered down.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If buffers are placed in AON domain islands along the path of isolation signals, then signal routing is enabled, but area increases and effectiveness is lost when routing distances exceed 2000 um
Solution Approach 1:
The patent introduces an intermediary mechanism (isolation signal routing through switchable domains using voltage level detection) to enable long-distance signal transmission without requiring extensive buffering infrastructure. This mediator allows signals to traverse through powered-down regions by detecting voltage levels and maintaining signal integrity without the need for continuous power supply along the entire path.
2Reliability
If AON buffers are designed as standard cells receiving both AON and switchable power supply, then signal routing is improved, but the AON power grid must run parallel to switchable power grid resulting in large area impact
Solution Approach 1:
The patent extracts the power supply requirement from the buffering function by allowing isolation signals to route through switchable domains that can be powered down. Instead of requiring AON buffers to have dual power supplies running parallel grids, the solution separates the signal routing function from the power supply function, enabling signals to pass through regions with different power states.
3Length of stationary object
If super buffers are used to route signals over the middle of the SoC, then long-distance routing is achieved, but area consumption increases and signals become susceptible to noise from power/ground shields
Solution Approach 1:
The patent introduces dynamic voltage level detection that adapts to the power state of domains along the signal path. The isolation signal routing mechanism dynamically adjusts its operation based on whether domains are in powered-on or powered-down states, enabling flexible long-distance routing without requiring static, noise-shielded infrastructure throughout the entire path.
4Loss of energy
If switchable domains are powered down during standby mode, then power consumption is reduced, but isolation signals cannot be reliably transmitted through these domains
Solution Approach 1:
The patent implements preliminary voltage level detection and signal preparation before domains are fully powered down. The isolation signal mechanism is pre-configured to detect voltage transitions and maintain signal integrity during the power transition period, ensuring reliable transmission even as domains switch between powered-on and powered-down states.
Data Source
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AI summary
In an integrated circuit, a first always on (AON) domain generates an isolation signal to enter standby mode. A switchable power domain propagates the isolation signal. A voltage level detector outputs an indicator which indicates whether a voltage of the switchable power supply is above or below a voltage threshold. An isolation wrapper circuit includes a pass-through latch selectively enabled based on the output of the voltage level detector. The pass-through latch receives the propagated isolation signal and provides a value of the propagated isolation signal at its output while enabled, but maintains a latched value at its output, regardless of changes in value of the propagated isolation signal, while disabled. The wrapper circuit also includes an isolation circuit which receives signals from circuitry within the switchable power domain and selectively isolates the received signals from a second AON power domain based on the output of the pass-through latch.