Apr 20th, 1:00 PM - 4:00 PM
Variable Gain Amplifiers Using Chalcogenide-Based Variable Resistors
Dr. Kris Campbell
A variable gain amplifier traditionally uses discrete component variable resistors, (e.g., potentiometer), on the output of a fixed gain operational amplifier circuit to control the gain. In class AB amplifiers the volume can be adjusted by varying this resistance, but due to the noise level in the output, the quality of the sound and efficiency of the amplifier is low. Chalcogenide based variable resistance devices are integrated circuit devices that have a wide variety of potential applications due to their low power consumption, ability to withstand radiation in harsh environments, high digital capacity, that is, the ability to retrieve data, and scaling. Due to these properties they have potential application in many consumer products (e.g., cell phones, computers, digital recorders), national defense, health and medicine, outer space, weather forecasting and so on. In our project, chalcogenide variable resistors (CVRs) are used to control the gain of a simple amplifier. These resistors are independently programmable. The advantage of the CVR in a circuit such as this variable gain amplifier is that the resistor can be fabricated in with the integrated circuit, thus creating a much smaller, lower power, and lower noise amplifier.