TITLE:
MMCC Based Electronically Tunable Allpass Filters Using Grounded Synthetic Inductor
AUTHORS:
Rabindranath Nandi, Palaniandavar Venkateswaran, Mousiki Kar
KEYWORDS:
Allpass Filter; MMCC; DVCCTA; CFA; Synthetic Inductor; Electronic Phase Shifter
JOURNAL NAME:
Circuits and Systems,
Vol.5 No.4,
March
28,
2014
ABSTRACT: New circuit
implementations of electronically tunable first and second order allpass filter
(AP) structures using a Multiplication Mode Current Conveyor (MMCC) building
block are presented. The control voltage (V) of the MMCC tunes the desired
phase (θ) while the time constant (τ) is adjustable by a Differential
Voltage Current Conveyor Transconductance Amplifier (DVCCTA)-based synthetic
lossless grounded inductor (L). The circuits are analyzed taking into account
the device imperfections which show low active
sensitivity features of the designs. The effects of port transfer error
(ε) and that of the parasitic
capacitances of the active devices had been meticulously examined which
indicated that certain deviations in nominal design equations occur; these however,
could be minimized with appropriate choice of the circuit passive components.
Readily available AD-844 type Current Feedback Amplifier (CFA) elements are
utilized for the topology implementation. Satisfactory test results on
electronic θ-tunability, upto about
300 KHz, had been verified by PSPICE simulation and with hardware
experimentation.