Noise diodes are used in noise source circuitry to produce white noise for calibrating many receiver applications. Gain, phase locking, noise figure and bandwidth can be monitored with appropriate noise sources.
M-pulse Microwave supplies noise diodes in chip or packaged form. The noise diode section on our website (MP3000 series) offers a selection of noise diode types and their ENR target values. The VBR window will be coupled with a recommended bias current for efficiently driving the diode noise floor.
For control ofNF:
NF (in db) = ENR-l OLog (Pout-l )
Pout is output in watts of DUT during the biasing cycle.
Another use of the noise diodes is in BITE (build-in-test-equipment). In this case the noise source is used to inject at the input of a potentially complex system some signal either through a directional coupler or by switching the input. This provides a simple way to check a system for major malfunctions.
Building in a synthesizer would be much more expensive and self test would take much longer since the noise source can generate simultaneously the whole frequency range of interest.