CMOS linear voltage-controlled positive/negative floating resistance configuration and its application in realising a voltage controllable all-pass filter

This letter presents a general CMOS linear voltage-controlled resistance (VCR) configuration, which can be configured as a voltage-controlled floating positive resistance (VCFPR) and a voltage-controlled floating negative resistance (VCFNR) by a simple artifice of changing two connections. The validity of this configuration has been demonstrated by SPICE simulations using 0.18-mu m CMOS process parameters. As an illustration of the utility of the proposed configuration, an application in which both VCFPR and VCFNR are utilised to realise a voltage tuneable all pass filter has been presented whose workability too has been demonstrated by SPICE simulations.