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Old 26th November 2009, 12:00 AM   #11
djank is offline djank  Ukraine
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put here the *.asc file
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Old 27th November 2009, 12:20 PM   #12
rcch87 is offline rcch87  Malaysia
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I managed to make the amplifier oscillate finally. I saw few hundreds of milivolts of Dc offset. Thanks for your help.

It is impossible to perform DC and AC analysis in this design. Am I right?

In order to calculate THD and IMD, what analysis that I needs to do ?
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Old 30th November 2009, 01:01 AM   #13
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There's another problem with your schematic: bottom end of C8 should connect to the node common to D6 anode, R24, U6 collector, U4 source etc., not to U8 cathode.

For frequency domain modelling, you can build a small-signal equivalent circuit, which can be helpful in terms of designing additional active loop-compensation. See Bruno's paper on the amplifier.

For modelling distortion, you could try a time-domain FFT analysis.

There aren't many components in the amplifier and PCB layout will play a significant role in its performance, so better to build it and measure it in real life
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Old 8th December 2009, 06:33 PM   #14
rcch87 is offline rcch87  Malaysia
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Default my imd

Hai..guys. I had successfully simulated my thd with .four . My thd is around 0.03 which is almost the same with the manufacture datasheet. I had simulated my IMD. But I had problem on how to determine the value of my IMD. I inserted a series voltage supplies , 9.5KHz and 10.5KHz in my Vin. Both of my sidebandsi amplitude is below -100db. My amplitude in the graph at 9.5KHz and 10.5Hz are both -33.dB . The rest are mostly below -100db. So can I know the way to determine my IMD?
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File Type: jpg IMDcircuit.JPG (289.0 KB, 137 views)
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Old 8th December 2009, 07:15 PM   #15
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You'll probably be interested in downloading the "Audio Measurement Handbook" from Audio Precision here: AP High Performance Audio Analyzer & Audio Test Instruments : Home, and this application note from Rane Audio: http://www.rane.com/pdf/ranenotes/Au...ifications.pdf

Last edited by HarryDymond; 8th December 2009 at 07:20 PM.
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