Variable Capacitance Diode (Varicaps, Varactors)

Function: A diode whose junction capacitance varies with applied reverse voltage.

Symbol: Similar to a standard diode with a capacitor-like addition at the cathode.

Key Parameters:

• C_j: Junction capacitance
• V_r: Reverse voltage
• C₀: Capacitance at zero bias
• γ (Gamma): Capacitance-voltage exponent

Applications:

• Voltage-controlled oscillators (VCOs)
• RF filters and tuning circuits
• Phase-locked loops (PLLs)
• Frequency modulators

Note: Operated in reverse bias; forward bias may cause damage.