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Q&A AD829 compensation capacitor

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AD829 compensation capacitor

volcano灿 on Aug 9, 2013

I use AD829 to realize inverting amplifier (Gain=-1). Figure 26 is the schematic. And I choose CLEAD=5pF,CCOMP=25pF as Table I shows.

But the output is strange, which is showed below.

Why will appear the phenomenon? Thank you for your answer.

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on Aug 12, 2013 6:29 PM over 8 years ago
Hi, volcano.

The recommended capacitor values are only guaranteed in ±15V supply voltage. Please use this supply voltage and let me know of your result. Also, if you could share your schematic with the AD829, that would be much better.

Regards,

Anna
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0 volcano灿 on Aug 13, 2013 11:56 AM over 8 years ago

Hi, Anna.

The above result is tested in ±15V supply voltage. My schematic and PCB(four layers) is shown below.

(four layers: signal, power, ground, signal)

Wait for your advice and explanation.

Regards,

volcano
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0 FormerMember on Aug 13, 2013 9:31 PM over 8 years ago

volcano,

What are the signal levels? Show us the scaling on the x and y axis of your scope shot.

Harry
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0 volcano灿 on Aug 14, 2013 7:19 AM over 8 years ago

Anna,

I finally find that the real +Vs pin voltage is +13V, so the supply voltage is +13V, -15V. Then I use the correct supply voltage ±15V, set CLEAD=100pF and CCOMP=25pF, and get the correct signal. Thank you for your sincere help.

volcano
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0 volcano灿 on Aug 14, 2013 7:22 AM over 8 years ago

Harry,

I finally find my mistake, the wrong supply voltage. Thank you for your concern.

volcano
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