ad734: General usage

Document created by analog-archivist Employee on Feb 23, 2016
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Problems with AD734
I've made the connections according to theFig.12 of Datasheet.
OpAmp - AD8066.
It shows 10 mv (peak-to-peak) noise with x=0, u=5v.
When I use X=U/N (N=2, 10, 100 formed by attenuator) and U=A +triangle(f=1MHz)
I got output =10/N +rectangular signal with amplitude about 10% of 10/N till U
was under 7V. At higher values of U the output was BAD.
In circuit shown in Fig. 9 I saw strange defect on the falling edge.
The input was in form - const(5V) + triangle (3V, 1MHz)  

 

The RTO (Referred To Output) noise is 1 uV/RtHz.
The bandwidth is 40 MHz so I would expect Rt40 (Approx = 6) mV of noise - this
is not much less than 10 mV.

I do not understand what signals you are applying and observing and describing
here:-

>When I use X=U/N (N=2, 10, 100 formed by attenuator) and U=A +
>triangle(f=1MHz) I got output =10/N +rectangular signal with amplitude
>about 10% of 10/N till U was under 7V. At higher values of U the output
>was BAD.

Please send a more detailed description with diagrams (preferably in .jpg
format).

With a signal frequency of 1 MHz you need a low load from the cathode of the
diode to ground (10 KOhm > LOAD > 1 KOhm) as described at the top of column 1
of page 8 of the AD734 datasheet.

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