MEASUREMENT OF FRACTIONAL IMPEDANCE USING SWITCHED CAPACITOR CIRCUITS

Abstract

This work provides, switched-capacitor (SC) realizations of the constant phase element (CPE) using the cadence TSMC 65 nm CMOS technology and MATLAB that could potentially be used in circuits for measuring fractional impedances. Two versions of the SC realizations are developed; using the bilinear discrete integrator (BDI) and composite discrete integrator (CDI)-based SC biquads. The realized CPE exhibits a constant phase in the frequency range 80 Hz to 10 KHz in its 4th order approximation. The normalized transfer functions obtained through continued fraction expansion (CFE) is further optimized through steepest descent technique for minimum phase errors. These SC realizations are simulated with low supply voltage of 0.7 V, the proposed realizations can be implemented for bio-medical applications that demand low voltage inputs and low power consumption (LVLP).