Sub-threshold Voltage Selection Circuit for Low Power
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Solution Overview
Problem
Conventional maximum voltage selection circuits rely on operational amplifiers that require dedicated bias circuits, leading to additional power consumption and inefficiency.
Innovation Solution
A maximum voltage selection circuit using a comparator with transistors operating in sub-threshold mode, including a power detection circuit and a latch circuit, dynamically monitors and switches between input voltages to minimize power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an operational amplifier is used to compare power supply voltages, then voltage comparison function is achieved, but additional power consumption occurs due to dedicated bias circuit requirements
Solution Approach 1:
The patent changes the operating parameters of transistors from standard mode to sub-threshold mode. By biasing the transistors in the sub-threshold region, the circuit achieves voltage comparison functionality with dramatically reduced power consumption, eliminating the need for power-hungry operational amplifiers and their dedicated bias circuits.
Solution Approach 2:
The patent replaces the operational amplifier-based voltage comparison mechanism with a transistor-based sub-threshold comparison mechanism. This substitution eliminates the need for complex bias circuits and operational amplifiers, achieving the same voltage comparison function with minimal power consumption through direct transistor operation in the sub-threshold region.
2Adaptability or versatility
If conventional maximum voltage selection circuit is used, then voltage selection function is achieved, but device complexity increases due to dedicated bias circuit
Solution Approach 1:
The patent merges the voltage comparison function and voltage selection function into a single integrated circuit block. By combining the sub-threshold transistor comparators with the selection logic in one unified structure, the patent eliminates the need for separate operational amplifiers and bias circuits, thereby reducing device complexity while maintaining full voltage selection capability.
Solution Approach 2:
The patent creates a multi-functional circuit where the same sub-threshold transistor structure performs both voltage comparison and voltage selection tasks. This universal approach allows the circuit to handle multiple input voltages and select the maximum without requiring separate dedicated circuits for each function, thus reducing overall device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution reduces power consumption by using sub-threshold transistors to compare and switch between input voltages, maintaining stable operation while minimizing additional power usage.
Implementation Method 1
uses a comparator that includes a plurality of transistors each operating under a sub-threshold mode (i.e., each transistor only conducts a sub-threshold current) to perform the comparison operation
Data Source
AI summary
A voltage selection circuit includes: a power detection circuit configured to compare an output voltage with a first input voltage and a second input voltage, respectively; a latch circuit, coupled to the power detection circuit, and configured to flip respective logic states of a pair of output signals when the output voltage is lower than either the first input voltage or the second input voltage; and a selection circuit, coupled to the latch circuit, and configured to use either the first input voltage or the second input voltage as the output voltage based on the respective logic states of the pair of output signals.