Design and Analysis of an Improved Translinear Floating Resistor for a Variable Gain Amplifier

An enhanced current controlled floating resistor design using a buffered mixed translinear loop based on the exponential current voltage relationship of the bipolar junction transistor is presented. The floating resistance varies from 1 k Ohm to 13 Ohms. Current controlled floating resistors have many applications in the design of electronically tunable analog circuits such as amplifiers, oscillators and active RC filters. This paper discusses the application of this floating resistor as a tuning stage of a variable gain amplifier. The variable gain amplifier has a voltage gain range from 1 to 7. The design was fabricated with National Semiconductor Corporation's vertically integrated complimentary bipolar technology (VIP10) and the test results are presented in this paper.