MOSFET-C current mode filter for secure communication applications

In this paper, a dual output current-mode biquad filter with band-pass and low-pass outputs using MOS transistors and capacitors is presented. In these type of filters MOSFETs operating in saturation mode are used instead of standard active elements and transconductances of these transistors are utilized instead of resistors. In the study a voltage controlled current source (VCCS) based core filter circuit is presented. This circuit is used as a starting point for the complete filter design. After VCCSs are replaced by MOSFETs biased for operating in saturation region, a resistorless MOSFET-C type filter circuit is obtained with only seven transistors and two grounded capacitors. Also, an agile filter application for secure communication is given to illustrate the functionality.