Hysteresis Voltage Comparator Circuit for Low Power Harvesting
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Solution Overview
Problem
Existing voltage comparison circuits in ambient energy harvesting systems consume excessive electrical energy, which is inefficient for low-energy resource systems.
Innovation Solution
A circuit design that compares an input voltage with a threshold using a configuration of transistors and resistors, including a feedback resistor to provide hysteresis operation, minimizing power consumption by only activating when the input voltage exceeds a specific threshold, and utilizing a capacitor for energy storage and inductive charging to optimize energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional voltage comparison circuit is used in an ambient energy harvesting system, then the circuit can perform voltage threshold detection, but the electrical energy consumption is excessive for low-energy resource systems
Solution Approach 1:
The circuit employs hysteresis operation that creates periodic switching action only when the input voltage crosses the threshold levels, rather than continuous operation. The feedback resistor Rf creates a memory effect where the circuit state changes periodically only when voltage thresholds are crossed, reducing power consumption by eliminating continuous comparison operations.
Solution Approach 2:
The feedback resistor Rf connects the output back to the inverting input, creating a hysteresis effect that provides feedback about the circuit's current state. This feedback mechanism allows the circuit to maintain stable threshold detection by comparing the input voltage against dynamically adjusted reference levels that depend on the output state, improving reliability while reducing unnecessary switching.
2Reliability
If the circuit activates continuously to ensure reliable voltage comparison, then detection reliability is maintained, but power consumption increases
Solution Approach 1:
The hysteresis configuration causes the circuit to activate periodically only when voltage thresholds are crossed, rather than continuously. The upper threshold Vu and lower threshold Vl create discrete switching events that occur only when needed, ensuring reliable detection while minimizing activation frequency and associated power consumption.
Solution Approach 2:
The reference voltage levels are made dynamic through the feedback mechanism, automatically adjusting between Vu and Vl based on the output state. This dynamic adaptation allows the circuit to maintain reliable comparison across varying operating conditions while consuming power only during actual threshold crossing events, not during stable operating periods.
3Device complexity
If a simple voltage divider configuration is used, then the circuit structure is simple, but the power consumption cannot be reduced effectively
Solution Approach 1:
The feedback resistor Rf is added to the simple voltage divider configuration, creating a minimal modification that introduces hysteresis. This single additional component transforms the circuit from a continuously active voltage divider into a periodically switching comparator, dramatically reducing power consumption while maintaining structural simplicity and avoiding complex circuit architectures.
Data Source
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AI summary
The invention relates to a circuit (100) for comparing a voltage (Ve) to a threshold, comprising: first (A) and second (B) nodes for applying said voltage; a first branch comprising a first transistor (T1) in series with a first resistor (R1) between the first and second nodes; a second branch comprising second (R2) and third (R3) resistors in series forming a voltage divider bridge between the first and second nodes, the midpoint (D) of the divider bridge being connected to a control node of the first transistor (T1); and a third branch comprising a second transistor (T2) in series with a resistive element (Rf), between the control node (D) of the first transistor and the first node, a control node of the second transistor being connected to the midpoint (C) of the series association of the first transistor (T1) and the first resistor (R1).