Texas Instruments CC400DK, User Manual, Page: 21 / 22

CC400DK Development kit (rev. 1.5) 2002-09-17 Page 21 of 22
Connect a Network Analyser to the unfiltered antenna output as shown in the figure, and
measure the impedance at the output.
Figure: Equipment set-up.
Set the CC400 transceiver in RX mode with the software program and adjust L51 and C61
until you measure approximately 50
Ω
impedance at the antenna output.
2) Transmitter tuning
Connect a Spectrum Analyser to the unfiltered antenna output in the same way as you did for
the RX tuning and measure output power. Set the CC400 transceiver in TX mode and adjust
C61 until you measure the highest output power.
3) Setting the Register bits
Choose the Register configuration window in the software.
1) If the optimum value of C61 found in RX mode is larger than C61 found in TX
mode:
Set bit F2 to 0 and increase bits F5 to F3 by an amount following the formula below
and update the device.
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛ −
=
pF
C C
round F F TX RX
25 . 1
61 61
3 : 5
Choose the value of C61 that you got from the TX tuning (C61
TX
).
Circuit board
PC
4-10V
Network analyser