Semiconductor Power-Supply Switching to Reduce Noise Spikes
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Solution Overview
Problem
Existing power-supply control methods in semiconductor integrated circuits face challenges in minimizing power-supply noise and operation delay due to accidental currents caused by leakages in MTCMOS technology, particularly when transitioning switch transistors from a stopped state to an active state.
Innovation Solution
A semiconductor integrated circuit design with switch transistors connected in parallel between voltage lines, where the switch conduction control section ensures that specific transistors with higher conducting-state resistance are put in a conducting state before those with lower resistance, and gradually increases the number of transistors and reduces time intervals for conduction control, to manage the transition from a non-conducting to a conducting state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If switch transistors are transitioned from non-conducting to conducting state simultaneously, then the conduction control operation is completed quickly, but power-supply noise peaks increase due to accidental currents from leakages
Solution Approach 1:
The patent segments the switch transistors into multiple groups based on their conducting-state resistance values. Instead of transitioning all transistors simultaneously, the control apparatus transitions different groups sequentially at different timing. This segmentation approach divides the large simultaneous current transition into smaller incremental steps, reducing peak power-supply noise while completing the conduction control operation in a controlled manner.
Solution Approach 2:
The patent applies preliminary action by transitioning switch transistors with higher conducting-state resistance before those with lower resistance. This ordered sequence ensures that transistors contributing more to leakage current are activated first, allowing the system to prepare for and manage the subsequent current flow from lower-resistance transistors, thereby minimizing accidental currents and power-supply noise peaks.
2Object-affected harmful factors
If switch transistors with higher conducting-state resistance are activated first, then power-supply noise is reduced, but the conduction control operation time increases
Solution Approach 1:
The patent employs dynamics by adjusting the timing intervals between transitioning different groups of switch transistors. The control apparatus dynamically determines the timing based on the resistance characteristics of each group, optimizing the sequence and intervals to balance noise reduction with operation speed. This dynamic approach allows the system to minimize power-supply noise while avoiding excessive operation time by adapting the transition schedule to the specific transistor characteristics.
3Power
If multiple switch transistors are connected in parallel, then the conducting-state resistance is reduced improving power supply efficiency, but the complexity of controlling their transition increases
Solution Approach 1:
The patent applies parameter changes by utilizing the conducting-state resistance values of different switch transistors as the basis for control timing. The control apparatus changes the timing parameter according to the resistance parameter of each transistor group, creating a systematic control strategy that manages the complexity of multiple parallel transistors through parameter-based differentiation rather than individual complex control logic.
Data Source
AI summary
A semiconductor integrated circuit includes: a first voltage line on which a specific one of a power-supply voltage and a reference voltage appears; a second voltage line; a plurality of circuit cells each receiving power generated as a difference between a voltage appearing on the second voltage line and the other one of the power-supply voltage and the reference voltage; a plurality of switch transistors connected in parallel between the first and second voltage lines to serve as switch transistors including switch transistors each having different conducting-state resistances; and a switch conduction control section for controlling a transition of each of the switch transistors from a non-conducting state to a conducting state by turning on the switch transistors at separate points of time.