Constant phase element explained

In electronics, a constant phase element is an equivalent electrical circuit component that models the behaviour of a double layer, that is, an imperfect capacitor (see double-layer capacitance).

Constant phase elements are also used in equivalent circuit modeling and data fitting of electrochemical impedance spectroscopy data.

A constant phase element also currently appears in modeling the imperfect dielectrics' behavior. The generalization in the fields of imperfect electrical resistances, capacitances, and inductances leads to the general "phasance" concept: http://fr.scribd.com/doc/71923015/The-Phasance-Concept

General equation

The electrical impedance can be calculated:

Z_CPE=

	1	=
	Y_CPE

	n
Q
	0\omega

-	\pi	ni
	2

where the CPE admittance is:

Y_CPE=Q_0(\omegai)ⁿ

and Q₀ and n (0[1]

Q₀ = 1/|Z| at ω = 1 rad/s

The constant phase is always −(90*n)°, with n from 0 to 1. The case n = 1 describes an ideal capacitor while the case n = 0 describes a pure resistor.

Notes and References

Kochowski. S. K. Nitsch. Description of the frequency behaviour of metal-SiO₂-GaAs structure characteristics by electrical equivalent circuit with constant phase element. Thin Solid Films. 21 May 2002. 415. 1–2. 133–137. 22 October 2012. 10.1016/s0040-6090(02)00506-0. 2002TSF...415..133K.