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AD8339 issue.

Question asked by JasonChien on Jul 14, 2016
Latest reply on Aug 7, 2016 by shengwuei

Dear Sir:

We have another about AD8339, could you help ?

 

There is DC bias problem on the outputs of AD8339, even when there is no signal input to AD8339.

The following figures show three consecutive ADC reading(1st/2nd/3rd) on our RX board, you can see there is a strange transient response during about sample 1~100, and there is a DC bias after sample 100, the DC bias are different on each ADC reading.

 

We had found :

  1. DC bias would be changed if RSET signal(4LO divider reset) is issued
  2. DC bias would be changed after each re-configuration of 20-bit shift register
  3. If RSET and 20-bit shift register is kept un-touched, DC bias would keep on the same level

1.png

2.png

Basically, we would expect there is NO DC bias when there is no signal input to AD8339(the ADC value should be zero plus some noise), which is not the case on our board.

Could you help on this ?

 

Thanks.

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