Power Supply Voltage Detection Circuit Offset Prevention
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Solution Overview
Problem
Existing power supply voltage detection circuits face challenges in preventing offsetting in differential pairs due to prolonged exposure to different voltages and high current consumption, which affects accuracy and circuit size.
Innovation Solution
A power supply voltage detection circuit design that applies the same bias voltage to the gates of transistors in a differential pair, eliminates the need for a voltage divider circuit by using clamp circuits with switchable clamp voltages, and incorporates a current mirror circuit for accurate reference voltage generation, reducing current consumption and circuit size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If different voltages are continuously applied to the gates of two transistors in a differential pair for an extended period, then the comparator circuit can compare voltages, but offsetting occurs in the differential pair causing detection inaccuracy
Solution Approach 1:
The patent applies equipotentiality by ensuring both transistors in the differential pair receive the same bias voltage at their gates. The bias voltage generation circuit provides identical bias voltages to both transistors, creating equipotential conditions that prevent offsetting and maintain differential pair stability during extended operation.
2Reliability
If current continues to flow through transistors or resistors in a voltage divider circuit to reduce consumption, then the circuit remains functional, but the circuit size increases and current consumption cannot be reduced
Solution Approach 1:
The patent applies periodic action by using switch circuits that periodically connect or disconnect clamp circuits based on power supply voltage levels. Instead of continuous current flow through voltage dividers, the switch circuits enable current to flow only when needed for voltage comparison, significantly reducing power consumption while maintaining circuit functionality.
3Use of energy by moving object
If the channel length of transistors or resistance value of resistors is increased to reduce current consumption in a voltage divider circuit, then current consumption decreases, but the circuit size increases
Solution Approach 1:
The patent applies dynamics by introducing switchable clamp circuits that dynamically adjust their connection state based on operating conditions. The switch circuits enable the circuit to adapt between different current paths, allowing small transistor sizes with moderate current consumption during active operation while maintaining low standby current, thus avoiding the need for large transistor channel lengths.
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
This design prevents offsetting in the differential pair, enhances detection accuracy, reduces current consumption, and minimizes circuit size while providing hysteresis characteristics, making it less susceptible to noise and power supply voltage fluctuations.
Implementation Method 1
a comparator circuit that generates an output signal indicating a result of comparison between the comparison voltage and the reference voltage, and that includes a first transistor and a second transistor that constitute a differential pair
Implementation Method 2
a first clamp circuit that has a first clamp voltage and is connected between a power supply node to which the power supply voltage is supplied and a source of the fourth transistor, and includes a switch circuit and a clamp circuit that are connected in parallel to the first clamp circuit
Data Source
AI summary
Provided is a power supply voltage detection circuit that prevents offsetting from occurring due to different voltages being applied for an extended period of time to gates of two transistors that constitute a differential pair in a comparator circuit that compares a comparison voltage that is generated based on a power supply voltage to a reference voltage. This power supply voltage detection circuit has a reference voltage generation circuit, a comparison voltage generation circuit, and a comparator circuit that includes a first transistor and a second transistor that constitute a differential pair and each have a gate to which a same bias voltage is applied, and a third transistor and a fourth transistor that are respectively connected in series to the first and second transistors and have sources to which the reference voltage and the comparison voltage are respectively applied.