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Category: Articles
Feedback Analysis by Marshal Leach
Here is a short write up by Marshal Leach (RIP) on feedback analysis. fdbkamps
Small Signal Audio Line Stage Buffer/Headphone Amplifier
This design, which I completed in 2010, takes an LM4562 and marries it to a hefty single ended class A output stage, which can be biased up for either 50 mA or 110 mA. The output stage is included in the global feedback network and can achieve 1 ppm at 20 kHz into 600 Ohms…
Stochino Feed Forward Amplifier – Wireless World 1994
This article decribes a feed forward amplifier concept from Giovanni Stochino. The design, while novel, is very complicated and delivers about 30 dB in distortion reduction. Stochino Feed Forward.pdf For an altogether simpler alternative that acheives about 20 dB distortion reduction, take a look at AFEC (‘augmented feedback error correction’) elswhere on this site.
The Quad 405 Current Dumping Amplifier from 1975
The famous Quad 405 ‘Current Dumping’ amplifier was launched in the mid 1970’s, and featured feed forward error correction that effectively removed the class B cross over distortion that plagues this type of output circuit structure. The design featured no adjustments in production, but the circuit components around the output (L2, R36, R38) had…
Michael Kiwanuka: SOA Protection for Audio Power Amplifiers
Power Amplifiers, and especially bipolar output designs, require output stage protection in the event of a fault, or the presence of a heavy or highly reactive load. Michael Kiwanuka explains the intricacies and the design methodology in his paper here soaprot_12-03-2012