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AD9824 VGA range setting code

Question asked by ricky on Jun 26, 2016
Latest reply on Jun 30, 2016 by ricky

Hi All,


I have a question on AD9824 data sheet.

In page 3, CCD-mode specification, the VGA gain is specified as next;

Low Gain (VGA Gain Code 77): 2dB

Max Gain (VGA Gain Code 1023): 36dB

On the other hand, page 15, in Table III, it seems that the Low Gain Code is 95, not 77.

Which is correct for the Low Gain VGA Code, 95 or 77?


Another question is the gain equation in Page 18.

It says that the VGA Gain is calculated as Gain= (0.0353) x Gain Code.

With this equation, Max Gain= 0.0353 x 1023= 36.1119, not 36.0dB.

Low Gain=0.0353 x 77= 2.7181, not 2.0dB.

How can we understand this difference between 36.1119 and 36, 2.7181 and 2?


Best Regards,