⌘K

Contents

Analog Communication

Amplitude Modulation

Amplitude Modulation Basics AM Frequency Spectrum AM Power Relations AM DSB-FC AM DSB-SC AM SSB VSB Modulation AM Modulators AM Demodulators Costas Loop

Frequency Modulation

FM Basics Bessel Functions in FM Carson's Rule PM Basics Narrowband FM Indirect FM Generation Direct FM Generation FM Demodulation Basics Foster-Seeley Discriminator Ratio Detector PLL Demodulator Pre-emphasis and De-emphasis Stereo FM

Noise Analysis

Noise Taxonomy Thermal Noise White Noise Signal to Noise Ratio Noise Figure Friis Formula Equivalent Noise Temperature Noise in AM Systems Noise in FM Systems FM Threshold Extension

Receiver Architectures

Receiver Parameters TRF Receiver Superheterodyne Receiver Image Frequency Rejection Double Conversion Direct Conversion Receiver Automatic Gain Control Tracking and Alignment

Pulse Modulation

Sampling Theorem Natural vs Flat Top Sampling PAM PWM PPM PCM Basics Quantization Noise Companding Delta Modulation Adaptive Delta Modulation DPCM

Analog vs Digital

Analog vs Digital Comm Hybrid Systems Applications Transition to Digital

Other Topics

Communication Channels Link Budget FDM TDM Television Basics

Other Subjects

Analog Electronics Digital Electronics Signals & Systems Control Systems Electromagnetic Theory Digital Communication Network Analysis Microprocessors VLSI Design Verilog HDL Power Electronics Embedded Systems DSP Electronic Devices

Section Progress54%

7 of 13 articles

Direct FM Generation

Varactor diode modulator, VCO.

Updated: 19 March 2026

9 min read

Direct FM Generation Quiz

Test your knowledge of varactor diode modulators, VCO operation, and direct FM generation circuits.

Question 1 of 3

Q1.In a varactor diode-based direct FM generator, the varactor is reverse-biased and placed in an LC tank circuit. As the reverse bias voltage increases, the depletion layer width increases. What is the effect on the oscillator frequency?

Related Articles

FM Basics

Frequency deviation, modulation index, narrowband vs wideband.

7 min read

Stereo FM

Multiplexing L+R and L-R signals.

9 min read

Bessel Functions in FM

Spectrum analysis, sideband amplitudes, carrier null.

4 min read

Narrowband FM

Approximation to AM, phasor representation.

10 min read

PM Basics

Phase modulation equation, modulation index.

4 min read

Indirect FM Generation

FM Demodulation Basics