AD8336_Power_Supply_issue

Document created by analog-archivist Employee on Feb 23, 2016
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One below customer is asking a question about AD8336. After his measurements,
he still cannot get
the gain value of 46db. But he mentioned, he cannot provide the -12V voltage
when the supply is +-12v.
So the current power supply for his application is from -9V to +12V, do you
think it is the root reason which
causes his problem?

 

1. There have been no production or failure issues reported for the AD8336 so
we will have to search for the problem and try to lead the customer to the
solution.

2. As you noted, the AD8336 is rated for supply voltages as high as +/-12V,
however it can also operate with supply voltages down to +/-3V. Under limited
conditions, the part will also operate to some degree with asymmetrical
supplies, although the designer needs to be very careful to not force output
voltage to exceed the maximum supply available. Of course, this assumes the
common-mode is 0. If the device is re-centered by offsetting the Vcm, the
output will also become symmetrical.

3.  Please notice the AD8336 is a variable-gain amplifier, which is to say, a
control voltage is required in order to attain the 46dB gain. Do we know the
control voltage the customer is using?

4. Do we know the environment of the AD8336? Is the customer measuring the gain
in an AD8336-EVALZ, or is he using his own circuit and environment?

5. Do we know the frequency?

6. Has the customer applied power to the device?

7. Do we know the input signal level applied to the device?

8. Do we know how the device is loaded?

9. Do we know the test circuit used?

10. Do we know the value of the gain he is seeing in his measurement?

11. Is the customer using an actual circuit or is he using a SPICE model?

12. I see there is a lot if information in Chinese below, perhaps some of the
above information can be found there.

13. Who is the customer?

As you can see there are a great many things to consider and review, any of
which would affect the results. Some of these questions may seem silly, but
last week I actually received a report of a problem, which turned out to have
occurred because the customer hadn’t turned on the power.

I could list a great many more questions but let’s see what results if any are
achieved from the above?

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