I am working on AD6676 chip ,and I am referring to Wideband IF Receiver Subsystem AD6676 Datasheet.
I have to change the default PIN_0DBFS value to -2.7dBm as per the specification provided for my project.So in order to change that I used the equation (2) & (4) given in pg no - 28 and 29 in the datasheet ,
PIN_0dBFS = 10 × log10(1/2 × RIN × IDAC1FS^2) ---> (2),
IDAC1FS = 4 mA × (IDAC1_FS/64) ----> (4),
I have set the following parameters as follows :
FIF => 258 Mhz,
BW => 56Mhz,
FADC => 3200Mhz,
Lext => 10nH,
IDAC1FS => 0x40 (0x10A register)
RIN => 60 ohm
Therefore considering all these above parameters ,as per the above equations ,I got PIN_0dBFS value as -3.18759 dBm theoretically.
But when we overwrite the IDAC1FS register(0x10A) ,we are not able to see any changes in the PIN_0dBFS value practically ,Is there anything that I have to take care so that I can see changes in the PIN_0dBFS.
Please do let me what changes needs to be done to obtain my PIN_0dBFS value as -2.7dBm
Also refer to this link as well because it also points to the same issue : AD6676 PIN_0DBFS calculation