I would be interested to test out if the balun/filter could be designed for Atmega128/256RFR2 series by using discrete components.
My plan for some future projects is to use a PIFA or other PCB antenna with a balun+filter made from discrete components. I guess this would be a quite good compromize regarding performance, component cost and board space requirements.
Is anyone aware of any example designs that could be of help? Especially for the balun design. I have seen the Atmel App Note "AT01030: Low-cost Ethernet to Wireless Gateway", but that uses a differential antenna which is WAY too large to be practical.