Interested in accurately simulating the noise of op-amp circuits? Burkhard Vogel wrote a book that addresses this relevant topic for any audio circuit designer who doesn't want to rely just on the manufacturer's own models.
Title: Slopes and Levels Spice Models to Simulate Vintage Op-Amp Noise
Author: Burkhard Vogel
ASIN: B09ZNYCRZ1
ISBN: 978-3-030-99443-3
Publisher: Springer (May 6, 2022)
Pages: 363
The first question that came to my mind when I read the title of Burkhard Vogel's book Slopes and Levels: Spice Models to Simulate Vintage Op-Amp Noise was why such a book would be required, given that op-amp manufacturers nowadays publish op-amp macromodels. Vogel answers that question convincingly: Some manufacturer-supplied models are way off. For example, he found a TL071 model featuring a flat equivalent input noise voltage density of 12 nV/V/Hz while a real TL071 is closer to 18 nV/VHz at 1kHz with a substantial increase below 100Hz. Another example is an NE5534A model with almost 6.5 nV/VHz of white voltage noise, when a real NE5534A typically produces 3.5 nV/V/Hz at 1kHz.
Vogel therefore started making his own LTspice op-amp noise models. He describes in detail what methods he used and what sanity checks he did to see if his models gave the expected results. The methods and equations are easy to understand once you get used to his notation, which doesn't take long, as it is logical and consistent.
The Beginning Chapters
In the first chapters, Vogel tries to use LTspice's UniversalOpamp2 model, but finds it too limited. The model only supports white noise and flicker noise with a slope of -10 dB/decade,
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