Sanctified Sinewaves: Jim Williams' Ultrapure Oscillator

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Jim Williams' latest (and last) attempt at perfection.

http://www.edn.com/article/519046-Test_18_bit_ADCs_with_an_ultrapure_sine_wave_oscillator.php

(I have had some difficulty making that link work. All I can suggest is, "Keep trying. Sisu. Illegitimi Non Carborundum.".
Or try < http://www.edn.com/file/26070-Test_18_bit_ADCs_with_an_ultrapure_sine_wave_oscillator_PDF.pdf > http://www.edn.com/file/26070-Test_18_bit_ADCs_with_an_ultrapure_sine_wave_oscillator_PDF.pdf. )

This is obviously the effort referenced in the thread, " Jim Williams designs a new Super Oscillator".


  • I see a fixed-tuned (2 KHz) Wien-Bridge variant with an analog optoisolator as the gain-control element.
  • An opamp-based precision rectifier circuit is used for amplitude detection.
  • The DC-offset is obviously there because of the end-application (testing A/D converters), but I don't know whether removing that feature would degrade performance.
  • The 130 ohm/0.47 uF lopass network on the output calls for a little thought and investigation.
  • A look at the "Notes" on the schematic tells you that "attention to detail" is important!
Dale
 
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