An Improved Physics-Based Formulation of the Microwave p-i-n Diode Impedance

An improved formulation of the frequency-dependent impedance for p-i-n diodes from physical and geometrical parameters is presented. This work is addressed to diode designers and allows them to evaluate quickly and accurately the diode impedance. It comes in parallel with existing SPICE p-i-n diode model used in CAD software. Under forward bias conditions, important recombinations occur in the heavily doped end regions of thin p-i-n diodes that seriously affects the diode impedance. This effect is taken into account to increase the accuracy of existing numerical models and to extend their validity domain to any I-region thicknesses. This improvement has been validated by measurement results on a 5-mum I-region width silicon p-i-n diode