Noise and Noise Figure Measurement

Plan of Attack

Thermal Noise

Noisy Resistor

Normalized Power Shows “How Much” Noise

Normalized Power Spectrum of Thermal Noise

Shot Noise

Shot Noise Power Spectrum

White Noise

A Noisy Circuit: Two Resistors

Adding the Noise Voltages

The Power Spectra Add

Generalization: A Passive Circuit

Active Circuit

Available Power

Available Power Spectrum

At Room Temperature

Filtering Noise

Noise Power

Filtering White Noise

Example: Low-Pass Filter

The Output Noise Power Depends on the Bandwidth

White Noise of Increasing Bandwidth

Some Illustrative Numbers

Continuing the Numbers...

Characterizing Two-Ports

A Noisy Two-Port Device

Defining Noise Figure

The Definition Requires a Room-Temperature Source

Cascade of Two-Port Devices

Overall Noise Figure

Cascade Example

Example, continued...

Example, continued...

Example, concluded

Input Signal-to-Noise Ratio

Output Signal-to-Noise Ratio

Lossy Two-Port

Lossy Line Example

Lossy Line Example, continued

Lossy Line, continued...

Lossy Line, concluded

Measurement of Noise Figure

Noise Sources

Excess Noise Ratio Example

Calculation of Noise Figure

Calculation, continued...

Example of Noise Figure Measurement

Example, continued...

Example, concluded

Example: Dynamic Range of an Optical Data Link

An Optical Data Link

Measured Gain Compression

Setup for Noise Figure Measurement

Measured Noise Figure

Minimum Detectable Signal Calculation

Compression Dynamic Range

A Caveat

Caveat, continued...

Caveat, concluded

Summary

Summary, continued...

Summary, concluded

PPT Slide