Varactor Diode Calculator

This page provides a Varactor diode calculator as part of a suite of converters and calculators. It helps determine key parameters for varactor diodes.

The calculator computes diode capacitance, cut-off frequency, and quality factor.

EXAMPLE:

INPUTS:

• Diode capacitance (Cj0) = 100 pF
• Barrier Potential (Vj) = 0.65 V
• Reverse bias potential (VR) = -4 V
• Series resistance (RS) = 12 Ohm
• Operating frequency (f) = 54 MHz
• m factor = 1/2

OUTPUTS:

• Diode capacitance at applied reverse bias (Cj) = 46.4 pF
• Cut-off frequency (fc) = 286 MHz
• Q (Quality Factor) = 5.29

Varactor Diode Equation

The following equation or formula is used within the Varactor diode calculator:

Cj = Cj0 / (1 + (VR / Vj))^m fc = 1 / (2 * π * RS * Cj0) Q = 1 / (2 * π * f * RS * Cj)