Noise Source and Noise Measurement Basics

Gregory covers the essentials of Noise Sources and Measurements, focusing on the use of a BJT transistor as a noise source. The BJT is configured with a reversed bias at its base-emitter junction, followed by a series of common-emitter amplifiers.

To analyze the noise at the circuit output, Gregory employs a Spectrum Analyzer with a noise marker function. This data is then used to estimate the BJT Excess Noise Ratio (ENR), factoring in the noise floor and amplification gain slope of the measurement setup.

The results are presented as Noise Power Densities and Noise Temperatures, chosen for their convenience in respective calculations. This approach allows for a straightforward yet thorough exploration of the noise characteristics.

BJT PN Junction Noise Source
https://gusbertianalog.com/bjt-pn-jun...

Video about Noise Temperature and SNR
   • Signal to Noise Ratio, Noise Temperat...  

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00:42 - Circuit overview
01:32 - Motivation for the measurements
02:54 - Noise characteristics
04:14 - Noise Power Density
05:48 - Reverse-biased base-emitter junction
06:46 - Spectrum analyzer measurement
08:08 - RBW and noise marker
11:24 - Automated measurements
14:54 - Amplifier gain de-embedding
17:10 - Excess noise ratio ENR
19:00 - Spectrum analyzer noise floor correction
23:04 - Circuit description
26:04 - Noise from Zener effect and Avalanche Breakdown