fell free to discuss or argue in case i'm missing something... ruling out DSO BW... this circuit is to analyze frequency response of a DUT, its loading effect to the source (R)... and opamps matching freq respond... opamps BW also can be verified. this is my version 2 refined from version 1, which originally intended to measure DUT freq respond (for bode plot analysis) without DSO BW affecting my measurement... ie respond = 20.Log(V3/V2) reading from DSO. cheers
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this is the thread and respond which lead me to this thread...
https://www.eevblog.com/forum/reviews/frequency-response-of-your-dso/Please tell us the details. ![Smiley :)](https://www.eevblog.com/forum/Smileys/default/smiley.gif)
easy! just use two 'almost matched respond' opamps as signal buffer (i used dual opamp package, BW comparable or higher than your scope's). split generator's signal to the 1st opamp and to (DUT to 2nd opamp). loading resulted by the DUT to the FG will be reflected in the 1st opamp too so DSO respond or loading effect... its taken care of, no worries
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but be sure to make as short traces as possible to rule out reflection and other black magic stuffs, those can be quite nasty and can cost you (me) another bald spot...
show both opamps signal on the scope and make your analysis. all we care is the difference (or ratio) between the two signals, its relativity! at particular freq, if the scope's respond is 3dB down, both signals will (should be) be 3dB down, but we already cancelled it by differentiating or rationalizing them. respond = 20.Log(V2/V1), doesnt matter if DSO is flat or not at that freq, the ratio should be the same... theoritically
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i kinda lazy to put it in my web (proper explanation) or here, so be pleased to ask anymore question if its not clear.
Regards,
Shafri.
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