Balun simulation of QN9021 BLE chip

[muhammadakramka]

Dear all, I am looking to simulate the balun circuit of QN9021 in ADS. But I don't know its differential input impedance (at its pins RFP and RFN).

Datasheet and App Note also does not tell anything about it. Hardware App note only shows the recommended L/C values which I need to verify through ADS simulations. Can anyone help me in finding the answers of the following: 1. What's the input impedance of the QN9021 chip at RFN and RFP pins 2. Why RVDD is connected to the Balun circuit in App note AN11814 (figure attached) Looking for your help.

Thanks

[mario_castaneda]

Hi Muhammad,

The impedance of the RF trace between matching network and antenna (or the SMAconnector) must be 50-Ω.
Why RVDD is connected to the Balun circuit in App note AN11814 ?

 As you know the QN902x series don't support balun, The uC has a external circuit L,C for this funtionality. The RVDD provides a better refence with ground and gives more control like the PA.

Hope it helps.

Best Regards,

Mario