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Category: Technical
The Monolithic Op-Amp: A Tutorial Study
This was an invited paper at the ISSCC in 1974 by James Solomon, who at the time worked for National Semiconductor (acquired in 2011 by TI). Those were heady days in semiconductors, with major process and circuit design breakthroughs taking place at breakneck speed. The general purpose microprocessors’ pivotal role in powering the Apple II…
Marshall Leach Opamp Tutorial
Marshall Leach (RIP) was a Professor of Electrical Engineering at Georgia Tech University best known for his Leach Amplifier which he used as a practical vehicle for teaching his students the finer details of analog design, feedback, thermal compensation and power electronics. Hundreds of Leach Amplifiers were built over the years by his students,…
The Alexander Amplifier
Mark Alexander’s eponymous creation was an early example of a high performance CFA amplifier and used an ADI integrated opamp and IGBT output devices in a novel circuit configuration that, at the time, yielded vanishingly low distortion and blistering speed. The ‘Alexander’ amplifier has been recycled by practitioners numerous times since its initial publication with…
12 point checklist for anyone using opamps in an audio design
Opamp User Guide V1.0.pdf
An Overview Of SID and TIM, Walt Jung et al
This series of articles on TIM and SID (and subsequent AES paper), were authored by Walter G. Jung and published between 1977 and 1979 in ‘The Audio Amateur’. It should be read in the context of amplifier design as it stood in the late 1970’s: a clear understanding of the mechanism was only just beginning…
Hifisonix Solid State Loudspeaker Relay
On big power amplifiers, conventional electromechanical relays leave much to be desired when it comes to their ability to reliably switch fault level currents in the event of a catastrophic amplifier fault. In a worst case situation (and I speak from experience), one of the output devices fails short circuit, placing the full amplifier rail voltage across the loudspeaker terminals. Relay…
Opamp Noise Visualizer
This Excel spread sheet tool was developed from one by Steve Hagman (www.AnalogHome.com) and allows en and ien data for up to 7 opamps to be compared. When using the tool, make sure you enter comparable data – so for example, always use the same frequency to make the comparison. I normally use 1 kHz…
Tom D Kite Busts Some Audio Myths!
Ever wondered how we got to ‘feedback is bad’, ‘ . . . sampling destroys the music’ or  ‘ . . .  analog is 40 bits resolution . . .’ ,  ‘we need damping factors of 1000’  and  ‘ . . . only vinyl sounds good’ ? Tom D Kite PhD, of Audio Precision, takes…
AN-597 Current Feedback Amplifiers
This National Semiconductor application note was written by Hans Palouda and published in 1989. It explains basic CFA operation clearly and concisely. AN-597 Current Feedback Amplifiers Here are some other useful application notes and articles that may help in developing an understanding of amplifier topologies and their associated trade-offs. wiki https://en.wikipedia.org/wiki/Current-feedback_operational_amplifier EDN https://www.edn.com/design/analog/4458753/In-defense-of-the-current-feedback-amplifier ADI https://www.analog.com/media/en/training-seminars/tutorials/MT-034.pdf TI https://cas.ee.ic.ac.uk/people/dario/files/E416/OA-30.pdf …
CFA’s: An Intuitive Analysis from Intersil
This application note from Intersil provides a simple and easy to understand explanation about CFA operation CFA – An Intuitive Analysis