To reduce the number of components and the cost, Texas Instruments offers a microstrip balun applicable for CC2420, CC243x, and CC2480. This design transforms the impedance of the differential signal at the RF pins of the radio to a single ended 50 ohm. Since the performance of this design depends very much on the layout of the microstrip lines, it is important to make an exact copy of the reference design.

This design note presents all the dimensions of the balun design to make implementation easier. In addition, an alternative way of copying the design by importing DXF or Gerber files is described.

http://www.ti.com/lit/swra098