New CMOS floating voltage-controlled resistor

A new CMOS floating voltage-controlled resistor for continuous-time filtering applications is described. The value of the resistance simulated by this circuit is independent of the threshold voltage of the transistors. This allows us to obtain a larger input range and also minimises the effects of threshold voltage mismatches and substrate noise. These improvements are obtained at the expense of a higher sensitivity to mismatches in the W/L ratios of the transistors.