Multiplexer Circuit for Power Supply Voltage Selection
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Solution Overview
Problem
Current semiconductor devices face challenges in reducing power consumption, particularly in systems-on-chip (SoC) where power islands operate at different voltage levels and frequencies, leading to inefficiencies in power management.
Innovation Solution
A multiplexer circuit is designed with selectable finger circuits that include an anti-leak transistor, a selector transistor, and a driver transistor, allowing for efficient selection and distribution of power supply voltages, reducing leakage paths and improving current capability by biasing transistors to the selected voltage level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If power islands operate at different voltage levels and frequencies to reduce power consumption, then power efficiency is improved, but leakage paths increase between different power domains
Solution Approach 1:
The power management circuit is segmented into multiple selectable finger circuits, each dedicated to a specific voltage level. This segmentation allows independent control of each voltage domain, enabling precise isolation of leakage paths while maintaining efficient power distribution to different power islands operating at different voltage and frequency levels.
Solution Approach 2:
An intermediary multiplexer circuit is introduced between different power domains to manage voltage transitions and isolate leakage paths. The multiplexer acts as a controlled intermediary that selectively connects different voltage levels to output nodes, preventing direct leakage paths while enabling efficient power management across multiple voltage domains.
2Device complexity
If traditional multiplexer circuits are used for voltage selection, then device complexity is reduced, but current driving capability is insufficient
Solution Approach 1:
Multiple transistor functions are merged into a unified selectable finger circuit structure. Each finger circuit combines selection transistors, driver transistors, and anti-leak transistors into an integrated unit that simultaneously performs voltage selection, current amplification, and leakage prevention, thereby enhancing current driving capability without proportionally increasing device complexity.
Solution Approach 2:
The multiplexer circuit employs dynamic transistor biasing where the body voltage of transistors is dynamically adjusted to match the selected voltage level. This dynamic adaptation enables the circuit to maintain optimal current driving capability across different voltage domains while preventing leakage paths, as the transistor characteristics are continuously optimized for the active voltage level.
Data Source
AI summary
A multiplexer circuit, of power supply (PS) voltages, includes: finger circuits correspond to the PS voltages, each selectable finger circuit (A) having an input node which is finger-circuit-specific and an output node which is common to the finger circuits, (B) including an anti-leak transistor of a first conductivity (C1) type, a selector transistor and a driver transistor transistors of a second conductivity (C2) type connected in series between the input node and the output node, and (C) being configured to receive a corresponding one of the PS voltages from the input node, and provide, if selected, a first version of the corresponding PS voltage to the output node.