Novel Active Circuit for Realizing Variable Grounded Passive Elements

This research paper presents a novel circuit configuration which can increase or decrease the value of an arbitrary grounded passive component. The proposed configuration employs two voltage differencing transconductance amplifiers (VDTAs) and does not require any passive component except the component to be scale. Hence, this configuration can be considered as a completely active circuit. The proposed circuit can increase/decrease the value of used passive component by a multiplication factor which includes the tranconductance gains of VDTAs. So, the value of passive element can be tuned electronically by varying bias currents. The presented configuration has several beneficial features such as no requirement(s) of component matching, low sensitivity indexes and excellent behavior under non-ideal conditions. The utilization of presented passive element multiplier has been validated by a high-pass filter design example. To verify the mathematical analysis, SPICE simulations have been performed with TSMC 0.18µm CMOS process parameters model.