Frequency Controls

Electronic components that control frequency include oscillators (crystal, LC, RC), capacitors, resonators, inductors, and varactors, working with active parts like op-amps in filters or VCOs to generate, stabilize, or select specific frequencies for timing and communication. Varactors (or varicap diodes) are specialized semiconductor diodes whose junction capacitance changes with applied reverse voltage, acting as a voltage-controlled capacitor, crucial for tuning circuits in radios, FM transmitters, phase-locked loops (PLLs), and frequency synthesizers, enabling electronic frequency tuning and modulation without mechanical parts.