Class A Buffering the Correct Way

Here’s a simple way to force an opamp output stage to run in class A when used with a discrete buffer output stage – it takes just 1 resistor to provide a near constant current source load. Operating the opamp (and the output buffer stage) in class A dramatically reduces harmonics on the power rail […]

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OPEX-1: A Discrete OPAMP for Audio

This design showcases a discrete opamp for audio applications.¬† It features very low noise, low distortion and a class A output stage that will deliver 1ppm distortion into¬† a 600 Ohm load at 12 V peak.   OPEX-1 Discrete Opamp

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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 […]

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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 […]

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