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Old 23rd March 2007, 11:01 PM   #1
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Default Opinions from amplifier analysers on these amp circuits

If some amp analysers can give some opinions on these two simplified amp circuits, I'm interested to know what you all think, the amps in question are used for current to voltage conversion after a dac chip, there is another amp after this to do the final driving of the output.

Cheers George
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Old 23rd March 2007, 11:02 PM   #2
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And the second amp.

Cheers George
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Old 24th March 2007, 03:46 PM   #3
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Schematics of opamps
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Old 24th March 2007, 06:29 PM   #4
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The first one looks like Scott Wurcer's folded cascode op amp. I think this is the architecture of the AD797. I think it is a very clever design. I wish I could claim it as one of mine.

You can learn more about it in AES preprint 3231
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Old 24th March 2007, 07:54 PM   #5
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Yes ADC they are opamps, I didn't want to preconceived ideas, so I purposely did not say they were, just want unbiased opinions on what people thought.

Cheers George
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Old 24th March 2007, 07:57 PM   #6
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have you read this http://www.passdiy.com/pdf/diyopamp.pdf
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Old 24th March 2007, 08:09 PM   #7
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Quote:
Originally posted by danville
The first one looks like Scott Wurcer's folded cascode op amp. I think this is the architecture of the AD797. I think it is a very clever design. I wish I could claim it as one of mine.

You can learn more about it in AES preprint 3231

The first one is Texas Instruments THS4031 very quick bipolar input and up to 100mA output capability.
http://focus.ti.com/lit/ds/symlink/ths4031.pdf

The second one is Analog Devices AD825 also quick fet input but up to 50mA output.
http://www.analog.com/UploadedFiles/...eets/AD825.pdf


I have a preference now for the THS4931 in the I/V stage even though the AD825 has been my favourite for the last 2 years, I was hoping that the circuit analysers of the forum could give technical reasons why?

Cheers George
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Old 25th March 2007, 09:32 AM   #8
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I like the first one better.
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Old 10th April 2007, 09:38 PM   #9
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Found a new one that AD built taking strong design for I/V conversion into account , note the input low impedance emiter loading, 2000vus slew rate and fast settling and 60mhz bandwidth. How does the schematic of this look for I/V?

http://www.analog.com/UploadedFiles/...eets/AD844.pdf



Cheers George
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Old 10th April 2007, 10:03 PM   #10
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Looks like a great choice for transconductance stage.
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