A JFET-based circuit for realizing a precision and linear floating voltage-controlled resistance

A JFET-based circuit for realizing a precision and linear floating voltage-controlled resistance (VCR) is presented for use in analog multipliers and programmable analog circuits and as a resistance mirror. It uses a matched JFET pair along with an op amp based negative feedback for realizing a precision resistance and a feedback of the source and drain voltages to the gate for realizing a linear floating resistance. The circuit operation is validated through circuit simulation and practical testing.