RF chip antenna for NRF52832

[Kapil]

Hi,

I have designed the Circuit using NRF52832 BLE and AT8010-E2R9HAA RF ANTENNA and tuned the circuit accordingly. Since the antenna was not available so I placed other RF antenna 2450AT43A100E from Johanson Technology Inc. www.digikey.com/.../1560838 Now I am facing issue for the range of BLE. Can someone suggest me about the tuning part for this antenna (2450AT43A100E)? What value I chose for inductor and capacitor for T network. I saw the datasheet but I am confused what value I should choose for this. I have chosen the value of T-network as L1=1.2nH C2= 1.5pF and C3=22pF.

Thanks in advance Regards Kapil

[Jørn]

Hello Kapil

If you look at page 545 of the nRF52832 product specification, you will find the reference circuits for the chip. On the antenna output there are two components, C3 and L1 (do note the differences between the QFx and the WLCSP package, choose the one you are using), these match the chip to 50 Ohm. So when you are looking into the antenna pin from outside the network you should see 50 Ohm. The T network you have chosen does not do this (it's located closer to 17-j47 Ohm for the QFx package), and causes a large mismatch between the nRF52832 and the antenna, which is specified to 50 Ohm. A mismatch like this will cause large attenuation, and greatly reduce your range.

The matching network is also there to correctly attenuate the harmonics, the matching network in the reference design is designed with that in mind.

I recommend you start by using the matching network stated in the product specification, and then use an additional network to match the antenna to 50 Ohm if needed.

Please see this tutorial for guidelines on designing a PCB with the nRF52. Do note that the RF part of the circuit is very sensitive to the layout of the PCB, and small errors can greatly affect your results. If you have a layout you would like us to review you can post it here on DevZone, or if your design is confidential you can create a mypage ticket at nordicsemi.com.

Best regards

Jørn Frøysa

[AmbystomaLabs]

You should post your artwork as Jorn suggests. Only by reviewing the artwork can we provide any meaningful feedback.