Microwave and Wireless Communications Technology

298 MICROWAVE DIODES

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DEPLETION ZONE

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,'1'1'

V V

(A) (B)

c~

~ I__ [

{C)

Figure ! 5-4

A) PN

diode at high-capacitance bias; B) low-capacitance bias;

C) equivalent

circuit.

where

Cj = diode capacitance

C = diode capacitance when the device is unbiased (V = 0), expressed in the

same units as Cj, and is a constant

V = applied reverse-bias potential

Vb = barrier potential at the junction (0.55 - 0.7 V in silicon)

m = constant that is material dependent (tends to be one-third to one-half)

K = a constant (often 1)

EXAMPLE 15-1

A silicon ...