Emulation of a constant phase element using operational transconductance amplifiers

The concept of emulating a constant phase element by an active scheme is presented in this work. Starting from a novel setup where the characteristics of the element could be easily derived, the emulation of the constant phase element is performed through a scheme that employs a differentiator and a voltage-to-current converter. The implementation of this scheme is done using operational transconductance amplifiers as active elements and uses grounded capacitors. The proposed emulator is accurate over five decades of frequency from (0.1 to 10 kHz) and offers independent electronic tunability of the constant phase element (i) magnitude (ii) phase angle and (iii) bandwidth of operation. Constant phase element designs currently available in the literature rely on using fixed passive RC ladder networks and thus lack flexibility and tunability. The behavior of the proposed design is verified through post-layout simulation results using Cadence and the 0.35 mu m CMOS process Design Kit provided by the Austrian Micro Systems.