CMOS Tunable Positive/Negative Floating Resistor Using OTAs

In an integrated circuit, a resistor can be achieved in silicon technology by using poly silicon of diffusion areas but a resistor of practical value based on this technique suffers the limitation of resistance value and also its resistance value can not variable. Moreover, only a positive resistor can be achieved from silicon technology. This paper presents a new tunable floating resistor using operational transconductance amplifiers (OTAs). Unlike the previously reported circuits, this circuit can realize a positive floating resistor and a negative floating resistor without changing the circuit topology which is highly suitable for implementation in CMOS technology. The simulated resistance value and either a positive or a negative resistor can be selected electronically by adjusting the biasing currents of OTAs. The workability of the proposed circuit is confirmed by PSPICE simulators. From simulation results, it can be expressed that the proposed circuit agrees well with theory.