Post Go back to editing

AuxiliaryADC decimation clock and resolution

Category: Hardware
Product Number: AD9364

I am using AuxADC in the AD9364 for reading external voltage reference at AuxADC pin (MAX_VALUE <= 1.3V-0.05V) using FMCOMM4 board. 

Doubt 1 - 

AuxADC Clock Frequency is set to 1024Mhz and AuxADC decimation to 1024. We are not able to understand the derivation of 3.906Khz clock at CTRL_OUT0 Pin (AuxADC decimation filter clock). What is the calculation behind it. Kindly elaborate

Doubt 2 - 

According to the datasheet the AuxADC is a 12bit ADC. According to my understanding : 

the resolution should be equal to = (1.3-0.05)V(Max input allowed) / 2^12 =   0.305mV

But, during lab testing we are seeing a offset as high as 0.2V between the input signal strength and read back value form the AuxADC (0x01E and 0x01F). 

Is there a need for calibration or any other offset input to ADC ?

Thread Notes