lcapy.oneport.CPE

class lcapy.oneport.CPE(K, alpha=0.5, **kwargs)

Bases: OnePort

Constant phase element

This has an impedance 1 / s ** alpha * K.

  • When alpha == 0, the CPE is equivalent to a resistor of resistance 1 / K.

  • When alpha == 1, the CPE is equivalent to a capacitor of capacitance K.

  • When alpha == 0.5 (default), the CPE is a Warburg element.

The phase of the impedance is -pi * alpha / 2.

Parameters:

  • K – Equivalent Capacitance or Conductance

  • alpha (float) – Exponent, with value from 0 to 1

K

Equivalent Capacitance or Conductance

alpha

Exponent, with value from 0 to 1

Type:

float

Notes

When alpha is non-integral, the impedance cannot be represented as a rational function and so there are no poles or zeros. So don’t be surprised if Lcapy throws an occasional wobbly.

Methods

__init__(K[, alpha])

Attributes