Question
I'm trying to use the Excel issue 2 signal chain calculator for the ADRF6518
and I'm not convinced it is working correctly, or I don't understand how to
enter the correct values into the calculation.
I can enter digital gains correctly but when I try and enter the VGA losses the
stage gain values just don't make sense. Looking at the cell that calculates
this value it has a very strange conditional statement in it. Could you take a
look at this and let me know if this is correct or if I can correct this by
modifying the cell to have a simple A-B value.
Answer
What you need to do is put in the digital gain values (which are put in with
their dB gain values) and then put in the analog voltage value (between 0V and
1V) for the VGN1, VGN2, and VGN3 pins (these cells are highlighted in yellow
below). The spreadsheet works exactly like how you would control the ADRF6518;
you don't have direct access to the attenuators. Instead you have control of
the attenuators via the analog gain pins.
Given the digtial gain values in dB and the analog gain pin values in Volts,
you then input a dBm number that you would apply on the input of the SMA
connector of the board (-60 dBm shown in yellow below), and/or you can put in a
dBV number at the input of the DUT itself (-40 dBV shown in yellow in the
second pic below). The rest of the cells show what the signal levels are at
the input and output of each stage and go red when you have reached their
max/compression level (below we have -60 dBm on the input of the SMA of the
evaluation board):
I apologize for the roughness of this tool. It need to be polished up a bit
for Rev 3.