⌘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 Progress60%

6 of 10 articles

Friis Formula

Cascaded noise figure calculation.

Updated: 19 March 2026

6 min read

Friis Formula Quiz

Test your ability to apply the Friis cascaded noise figure formula to multistage amplifier chains.

Question 1 of 3

Q1.For a two-stage cascaded system with noise figures F1, F2 and available power gains G1, G2, the overall noise figure according to Friis formula is:

Related Articles

Noise in FM Systems

Figure of merit, capture effect, threshold effect.

5 min read

Thermal Noise

Johnson-Nyquist noise voltage, bandwidth dependence.

5 min read

Noise in AM Systems

Figure of merit, coherent detection SNR.

9 min read

Noise Taxonomy

External vs Internal, Shot, Thermal, Flicker, Burst noise.

10 min read

White Noise

Power spectral density, autocorrelation.

5 min read

Equivalent Noise Temperature