Programmable CMOS active resistor using computational circuits

A new active resistor circuit will be further presented, having the main advantages of an improved linearity and of a small area consumption. An original technique for linearizing the current-voltage characteristic of the active resistor will be proposed, based on the utilization of a MOS differential amplifier, whose transfer characteristic is linearized using an original biasing. The controllability of the active resistor circuit is excellent, being possible to modify the circuit equivalent resistance by changing the value of the biasing current. The proposed structure allows the implementing of a circuit having a negative equivalent resistance using an original cross-connection between input and output.