Hello,
Can you please provide the input impedance or the S-parameter file of the impedance for the nrf52840 for receive mode, and also at tx power levels of -40dBm, 0dBm, and 5dBm?
We request this data the Ant port of the module, before the recommended matching/filter components provided in the reference design.
Thanks Sasidhar
The output impedance of the ANT pin of the nRF52840 at TX power of 0dBm is 115.771 + 33.357j ohms.
See page 3 of Nordic's measurement file nRf52840 QIAA matching network.pdf (in the .rar compressed file linked in this thread). Their measured value looking into the matching network from the ANT pin is 115.771 - 33.357j ohms.
The impedance of the matching network (0.8pF shunt, 3.9nH series) of the suggested nRF52840 layout is 111.8 - 32.9j with a 50 ohm load, which verified the measured number above. The complex conjugate should be the impedance of the ANT pin.
The impedance of the ANT pin seems to be different for TX powers other than 0dBm, but this is the most common transmit power.
The output impedance of the ANT pin of the nRF52840 at TX power of 0dBm is 115.771 + 33.357j ohms.
See page 3 of Nordic's measurement file nRf52840 QIAA matching network.pdf (in the .rar compressed file linked in this thread). Their measured value looking into the matching network from the ANT pin is 115.771 - 33.357j ohms.
The impedance of the matching network (0.8pF shunt, 3.9nH series) of the suggested nRF52840 layout is 111.8 - 32.9j with a 50 ohm load, which verified the measured number above. The complex conjugate should be the impedance of the ANT pin.
The impedance of the ANT pin seems to be different for TX powers other than 0dBm, but this is the most common transmit power.
