Hi Dialog !
I have designed a folded IFA which is tuned at 2.45 Ghz for two layers. I have seen that yours IFA that you proposed on pcb trace antenna has a Pi matching circuit.
In the application note you say that:" The RF port is single ended 50 Ω, so no external balun is required". So why do you use the matching circuit?
Can I plug my antenna to the RFIOP without using a matching circuit?
提前谢谢!
Device:
Hi l00ver1,
when you are sure that your antenna has its resonance at 2440 MHz, and has a good matching to 50 Ohm, then it is okay to connect the antenna to the RFIOp port directly.
The RFIOp port of the DA14580 is not a nicely 50 Ohm, that's why we match it to 50 OHm by introducing a shunt inductor of 3.3nH or 3.9nH.
The WLCSP DA14580 RFIOp output has about 25 -J25 Ohm impedance, with a 3.3nH shunt inductor the output impeance is a nice 50 OHm.
The QFN packages require a 3.9nH shunt inductor.
Place this shunt inductor as close as possible to the DA14580 RFIO pins.
Best regards, BB_Dialog/
What kind of shunt inductor is needed for the DA14583?
Hi ddustin,
The 583 has a QFN package so the inductor needed is a 3.9nH inductor.
Thanks MT_dialog
Should the inductor go to ground or be in line?
Thanks!
Dustin
Hi ddustin,
You can have a look at our schematics for our reference designs or development kits that use the 583 and check the connection and the value of the inductor.
Thanks MT_dialog
Hi,
我在看reference design for the 583 IoT Sensor Board Schematic (attached here for reference).
The RFIOp line goes through the matching circuit to the antenna. The first inductor is inside the matching network, R25.
There is no inductor near RFIOp going to ground. Perhaps the schematic is missing the inductor?
Cross checking document AN-B-027, seems to confirm an inductor is needed next to the RFIOp pin. Based on this quoted text:
● L1: 3.9 nH, 0402, LQP series, Murata
● L2: 5.1 nH, 0402, LQP series, Murata
● C1, DNP
● In addition to the matching a network, a 3.3 nH or 3.9 nH coil (depending on the DA14580 package) is additionally required close to the RFIOp pin.
Can you confirm adding an extra 3.9nH inductor from RFIOp to ground is needed, even though it is missing from the attached schematic?
Thanks!
Dustin
Hi ddustin,
These inductors came out a bit later, and yes, in order to make the 58x RFIOp port 50 Ohm, its required, please have a look at the Pro-kit daughter board of the 583, UM-B-034 figure 27.
Thanks MT_dialog