CC2520_11 Datasheet, PDF (29/133 Pages) Texas Instruments – 2.4 GHZ IEEE 802.15.4/ZIGBEE RF TRANSCEIVER

CC2520 DATASHEET
2.4 GHZ IEEE 802.15.4/ZIGBEE® RF TRANSCEIVER
SWRS068 – DECEMBER 2007
9 Application Circuit
Very few external components are required for the operation of CC2520. A typical application circuit is
shown in Figure 4. Note that it does not show how the board layout should be done. The board layout will
greatly influence the RF performance of CC2520.
This section is meant as an introduction only. For further details, see the reference design, which includes
complete board layouts and bill of materials with manufacturer and part numbers. The reference design can
be downloaded from the CC2520 product folder [7].
Note that decoupling capacitors are not shown in the figure below. See the reference design for complete
bill of materials.
Figure 3: Typical application circuit with transmission line balun for single-ended operation
See the antenna selection guide [12] for further details on other compact and low-cost alternatives.
9.1 Input / Output Matching
The RF input/output is high impedance and differential.
When using an unbalanced antenna such as a monopole, a balun should be used in order to optimize
performance. The balun can be implemented using low-cost discrete inductors and capacitors only or in
combination with transmission lines replacing the discrete inductors.
Figure 4 shows the balun implemented in a two-layer reference design. It consists of three transmission
lines (L1, L2 and L3) and the discrete components C191, C171, C192, C173 and C174. The circuit will
present the optimum RF termination to CC2520 with a 50Ω load on the antenna connection.
WWW.TI.COM
29