FET Resistance Control with Temperature-Based Gate Voltage Correction
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Solution Overview
Problem
Existing technologies do not provide a method for determining the gate voltage at which the difference between the threshold voltage and the gate-source voltage of a field-effect transistor becomes a constant value at various temperatures, leading to temperature dependence of the drain-source resistance.
Innovation Solution
A resistance device comprising a field-effect transistor and a voltage applying circuit that applies a control voltage obtained by adding a correction voltage to a reference voltage, where the correction voltage varies linearly with temperature, to control the resistance value between the drain and source of the field-effect transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a field-effect transistor is used as a feedback resistor, then the resistance value can be controlled by gate voltage, but the drain-source resistance becomes temperature dependent due to threshold voltage changes
Solution Approach 1:
The patent applies parameter changes by adjusting the gate voltage based on temperature to compensate for threshold voltage drift. Specifically, the gate voltage is changed as a function of temperature to maintain a constant (Vgs-Vth) difference, thereby stabilizing the drain-source resistance against temperature variations while preserving the controllable resistance feature.
2Reliability
If temperature correction is applied to stabilize drain-source resistance, then temperature dependence is reduced, but the method for determining correction values at multiple temperatures is not provided
Solution Approach 1:
The patent employs preliminary action by pre-determining and storing the relationship between temperature and gate voltage correction values in a lookup table or memory structure. This allows the correction values to be readily available during operation without requiring complex real-time calculations, thus reducing device complexity while maintaining temperature stability.
3Reliability
If the gate voltage is adjusted to compensate for threshold voltage changes, then the resistance value can be stabilized, but the specific method for determining the correction voltage at various temperatures is not described
Solution Approach 1:
The patent determines and stores the correction voltage values in advance for multiple temperature points, creating a pre-computed lookup table that maps temperature to required gate voltage adjustments. This preliminary determination eliminates the need for complex real-time measurement and calculation during operation, reducing the difficulty of detecting and measuring the required correction voltage.
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
Enables efficient determination of a combination of correction factors for the control voltage across the gate and source of the field-effect transistor, reducing temperature dependence of the desired physical quantity, such as resistance value.
Implementation Method 1
when the gate-source voltage Vgs of the field-effect transistor is constant, the drain-source resistance Rds decreases as the temperature thereof increases due to change in a threshold voltage Vth
Data Source
AI summary
A resistance device (100) includes a field-effect transistor (TN) and a voltage applying circuit (1). The voltage applying circuit (1) applies a control voltage (Vgs) between the gate and source of the field-effect transistor (TN) according to a temperature (T) to control a resistance value (R) between the drain and source of the field-effect transistor (TN). The control voltage (Vgs) is a voltage obtained by adding a correction voltage (Vc) to a reference voltage (Vgs0). The correction voltage (Vc) depends on the temperature (T) and is set to be zero at a first temperature (T1).