Voltage mode multifunction OTA-C biquad filter

Purpose - To develop an OTA-C-based universal filter realizing all standard transfer functions viz low pass, high pass, band pass, notch and all pass without an inverting amplifier and with minimum component matching condition. Design/methodology/approach - By developing different sets of current and voltage relationship involving simple independent transconductance in biquadratic functions using three operational transconductance amplifiers the aim has been achieved. Findings - The circuit produces all pass transfer function as stated above without inverting amplifier as has been used in most of the earlier circuits. All realizations except all pass filter requires no matching condition. The circuit remains stable for non-ideal OTAs. Originality/value - The proposed circuit finds wide utility in industrial and research applications as a signal processing element.