MSU Technologies

Voltage-controlled Resistor Device Based on Phase Transition Materials

Introduction

Circuit designers often require a resistor that consistently alters its resistance based upon an input control voltage. A voltage-controlled resistor (VCR) is a three-terminal device that varies the resistance between two terminals relative to voltage in the third terminal. VCRs are commonly used in the following electronics: variable gain amplifiers, voltage-controlled oscillators, automatic gain controllers, low-distortion tunable filters, dynamic range compressors, and electronically-controlled phase advance/phase retard circuits. In all of these applications, it is essential that the resistor can alter its value based upon the input voltage.

Description of Technology

This technology is a voltage-controlled resistor composed of Vanadium Oxide (VO₂), a material that demonstrates a variable resistance with change in temperature. While this materials variable resistance has been well documented and used in various circuit design applications, it has never been used as the source of variable resistance itself. The proposed circuit design is just one of many possible design solutions that could use a VO₂ resistor. The circuit uses a platinum heater, feedback VO₂ resistor and a controller to adjust the power input into the heater. Power to the heater would increase or decrease to achieve a certain resistor temperature, and in turn the resistance. The feedback resistor would ensure that the power is adjusted as necessary to maintain the desired resistance.

Key Benefits

Large Range: This resistor has a large voltage and resistance range
Response Time: This device has a very quick response time of 10 ms
Small Power Consumption: Requires less than 1 mW of power for operation
Size: This device is smaller in size than LED-photoresistor pairs, another type of VCR
Manufacturing: This device can use existing manufacturing methods for creation and assembly

Applications