EVM Circuit Overview
www.ti.com
The TRF2443 RX path allows the use of an external SAW filter. An internal switch, which is programmable
through the serial interface, gives the flexibility to utilize the external filter (see
Figure 1
). The internal
switch is controlled via the serial programming interface through bit EN_SAW. By programming EN_SAW
to 1, the external path is selected, whereas a 0 engages the internal bypass switch. When EN_SAW is set
to 1 the IF signal will be routed out of the IC to SMA connector J30 (IFOUT) (see
Figure 8
). At this point,
the user has the flexibility to insert a filter of choice outside the TRF2443 EVM. (The board does contain a
place holder (FL1) for a SAW filter but is not populated. In this way, the user has the flexibility to use a
filter of his choice). For initial evaluation, an 8-10 dB pad can be used in lieu of a filter to emulate the
insertion loss of a typical filter. The user must route the signal from J30 (IFOUT) to J31 (IFIN) with the filter
or pad included.
Figure 8. SAW Filter Path
List of Tables
8
SLWU065 – September 2009
Submit Documentation Feedback
