Question
We have made and are using RF modules based on the ADF7021 with it's internal
Rx/Tx switch. So far we are very satisfied with its performance. But we would
like to go one step further and build a module with an external Rx/Tx switch
(ADG919). I know that there are parasitic capacitance and inductance dependent
from a specific pcb layout but any way are there any pre calculated values
for matching LC networks for 433MHz, 868MHz and 915Mhz frequencies for such
design? Or are there any demo boards or not yet published documents for using
external switch? We need sample values for a seperate match network. We would
like values
for both designs: with external PA and with internal PA. Output power
requirement (with external PA) is 100mW. Which external PA do you recommend?
Is it possible to use Freescale MBC13916 :
http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=MBC13916&lang_cd=
en&webpageId=M10Mld5Hf&nodeId=0106B98699d5Hf&fromPage=tax
Answer
We do not have sample values other than the daughtercard designs. The
ADF7021DBZ9 board with a separate match will be informative. Please find the
latest Eval Note PDF attached. It supersedes the PDF currently found in the
ADF70xx Evaluation Software download on analog.com. It includes the DBZ9
schematic.
We do not recommend specific PAs, although we have worked with Skyworks and
RFMD in the past with other parts.
For PA selection please look at the Application Note on RF Port Impedance
Matching and External Component Selection which will be very useful.
https://www.analog.com/static/imported-files/application_notes/AN-859.pdf