Electronically Controllable Resistor Circuit for Stable Low-Ohmic Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electronically controllable resistors (ECRs) face limitations in achieving precise resistance control, especially at low values, due to narrow voltage ranges, temperature dependence, and instability under destabilizing factors, restricting their application in electronic circuits.
Innovation Solution
The proposed ECR design incorporates a voltage converter with three inputs, an instrument resistor, and a subtractor, along with an executive element, allowing for precise resistance control through an intermediate voltage signal generated by multiplying high-potential voltage by the ratio of controlling voltages, enabling both direct and inverse dependence on controlling voltage, and accommodating small resistance values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional FET-based ECR design is used, then the device structure is simple, but the resistance control accuracy is poor and the voltage range is narrow
Solution Approach 1:
The ECR is segmented into multiple functional modules: a FET-based variable resistor for resistance adjustment, a voltage converter for precise controlling voltage generation, and a subtractor for voltage difference calculation. This modular segmentation allows each component to specialize in one function, improving overall resistance control accuracy while maintaining reasonable device complexity
Solution Approach 2:
A voltage converter is introduced as an intermediary component between the control input and the FET gate. This intermediary converts the controlling voltage into a precise form that accurately controls the FET channel resistance, thereby improving resistance control accuracy without requiring direct complex control circuitry
2Ease of manufacture
If a simple FET-based ECR is used, then the device is easy to manufacture, but the temperature stability is poor
Solution Approach 1:
A subtractor is implemented to calculate the voltage difference between the actual controlling voltage and the required controlling voltage. This feedback mechanism continuously monitors and adjusts the controlling voltage to compensate for temperature drift and other destabilizing factors, improving temperature stability while maintaining manufacturing simplicity
Solution Approach 2:
The ECR employs dynamic voltage adjustment through the voltage converter and subtractor combination. The system dynamically adapts the controlling voltage in real-time to counteract temperature variations, transforming a static simple FET structure into a dynamically stable resistance control system
3Adaptability or versatility
If a FET-based ECR with parallel resistor is used, then the resistance range is extended, but the control accuracy deteriorates under destabilizing factors
Solution Approach 1:
The voltage converter performs preliminary action by pre-calculating and generating the exact controlling voltage needed before it is applied to the FET. This preliminary voltage conversion ensures that the FET receives the precise voltage required for the desired resistance value, maintaining control accuracy across the extended resistance range achieved by the parallel resistor configuration
4Device complexity
If conventional ECR designs are used, then the device complexity is low, but the resistance value depends on source-drain voltage
Solution Approach 1:
The voltage converter acts as an intermediary that decouples the relationship between source-drain voltage and controlling voltage. It converts the source-drain voltage along with control signals into a precise controlling voltage that independently sets the FET resistance, eliminating the direct dependence of resistance value on source-drain voltage fluctuations
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 achieves wide-ranging resistance values, including low ohmic resistances, with high tolerance to temperature variations and destabilizing factors, enabling precise control of resistance in electronic circuits.
Implementation Method 1
a voltage converter, whose first input is connected to a terminal of the ECR meant for being connected to a first source of controlling voltage, and whose third input is connected to the high-potential terminal of the ECR; the voltage converter being adapted to multiply the high-potential voltage by a ratio of a value of one controlling voltage to a value of another controlling voltage
Data Source
AI summary
An electronically controllable resistor (ECR) designed for changing the resistance of a portion of a circuit comprises a voltage converter, a subtractor, an instrumental resistor (IR), and an executive element (EE) which can include at least one MOSFET or IGBT or a vacuum tube. There are a high-potential and two control voltage sources. The converter, which can use logarithmic amplifiers or be digital, is adapted to multiply the high-potential voltage by one of the control voltages and divide by another one. The resulting intermediate voltage is applied to the subtractor and compared therein with a voltage drop on the IR created by the current flowing through the IR and the EE. Thus, the ECR resistance can be regulated. The ECR makes it possible to achieve a wide range of resistance values, down to ultra-small values, while maintaining tolerance to destabilizing factors, including temperature. Also claimed is an ECR control circuit.