Electronically Tunable Current Mode Second Order High Pass Filter with Variable Central Frequency /o

摘要

At present, there is a growing interest in designing capacitor-less, resistor-less current mode active only filters using only active elements such as Operational amplifier [OA], Operational transconductance amplifiers [OTAs]. Current mode filters have many advantages compared with their voltage mode counterparts. Current mode filters have large dynamic range, higher bandwidth, greater linearity, simple circuitry, low power consumption etc. A novel single-input current-mode active-R filter using two operational amplifiers (OAs) and resistors is presented. The circuit is fully programmable and implements high pass (HP) functions. The availability of currents at high impedances facilitates cascadibility feature. The filter performance factors center frequency (ω_o), bandwidth (ω_o/Q), quality factor (Q) and gain (G) are electronically tunable. The SPICE simulation results are included to confirm the workability of the proposed circuit. This circuit can realize quadratic transfer function. Paper includes theoretical frequency response of second order high pass filter for cut off frequency 50 k with variable Q. The circuit is suitable for high frequency operation and monolithic integration. The proposed second order high pass filter works ideal for Q = 10 and central frequency from 1 kHz to 50 kHz. The gain roll-off is 40 dB/decade. The designed filter has passive sensitivities less than unity magnitude and active sensitivities half in magnitude.