Additional Filtering; Power Supply Decoupling; Antenna Considerations - Texas Instruments CC1101 Manual

and C101 can be omitted when using a
7.5

Additional Filtering

In the 868/915 MHz reference design, C126
and L125 together with C125 build an optional
filter to reduce emission at carrier frequency –
169 MHz. This filter
applications with an
connector that seek compliance with ETSI EN
300-220. For more information, see DN017 [9].
7.6

Power Supply Decoupling

The power supply must be properly decoupled
close to the supply pins. Note that decoupling
capacitors are not shown in the application
circuit. The placement and the size of the
7.7

Antenna Considerations

The reference design ([1] and [2]) contains a
SMA connector and is matched for a 50 
load. The SMA connector makes it easy to
connect evaluation modules and prototypes to
different test equipment
Component Description
C51 Decoupling capacitor for on-chip voltage regulator to digital part
C81/C101 Crystal loading capacitors
C121/C131 RF balun/matching capacitors
C122 RF LC filter/matching filter capacitor (315/433 MHz). RF balun/matching capacitor (868/915 MHz).
C123 RF LC filter/matching capacitor
C124 RF balun DC blocking capacitor
C125 RF LC filter DC blocking capacitor and part of optional RF LC filter (868/915 MHz)
C126 Part of optional RF LC filter and DC-block (868/915 MHz)
L121/L131 RF balun/matching inductors (inexpensive multi-layer type)
L122 RF LC filter/matching filter inductor (315 and 433 MHz). RF balun/matching inductor (868/915 MHz).
(inexpensive multi-layer type)
L123 RF LC filter/matching filter inductor (inexpensive multi-layer type)
L124 RF LC filter/matching filter inductor (inexpensive multi-layer type)
L125 Optional RF LC filter/matching filter inductor (inexpensive multi-layer type) (868/915 MHz)
L132 RF balun/matching inductor. (inexpensive multi-layer type)
R171 Resistor for internal bias current reference
26 – 27 MHz crystal
XTAL
Table 20: Overview of External Components (excluding supply decoupling capacitors)
is necessary for
external antenna
for example a
SWRS061H
reference signal.
If this filtering is not necessary, C125 will work
as a DC block (only necessary if there is a DC
path in the antenna). C126 and L125 should in
that case be left unmounted.
Additional external components (e.g. an RF
SAW filter) may be used in order to improve
the performance in specific applications.
decoupling capacitors are very important to
achieve the optimum
CC1101EM reference designs ([1] and [2])
should be followed closely.
spectrum analyzer. The SMA connector can
also be replaced by an antenna suitable for
the desired application.
antenna selection guide [13] for further details
regarding antenna solutions provided by TI.
CC1101
performance. The
Please refer to the
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