0433BM15A0001E Datasheet, PDF (13/27 Pages) Johanson Technology Inc. – Johanson Technology Matched Balun Filters for CC110x & CC111x

Design Note DN025
As can be seen in Figure 11; there are some higher order harmonics that exceed the FCC
limit of -41.2 dBm. If this was the case in the application; then equation 1 could be used to
correlate the level by not continuously transmitting.
In theory, performing the test with a 4-layer FR4 PCB with a ground plane on layer 2, will give
a better performance since the pre-preg is typically 80-100 um thick and this will give a better
grounding and amount of radiated energy will be less compared to a similar design on a 2-
layer. Even when several pre-preg layers will be used between layer 1 and layer 2 on a 4-
layer FR4 PCB; the thickness will generally be less than 0.8 mm, so the radiated performance
will be better.
3.3.1.4 Summary of Measurements
Use of an LC filter does not affect the sensitivity or the output power measurements
significantly. For the total link budget, there is an advantage using the LC filter for the
sensitivity and a slight power loss for the output power. Therefore, the total effect of the LC
filter on the system performance will be the same. However, the main benefits of the LC filter
are the suppression of the harmonics.
When deciding which configuration should be used, the following should be considered:
There are mainly two power applications categories with 10 dBm and 0 dBm; there are FCC
and ETSI regulatory requirements; and also if conducted emissions will also be tested in the
final application (i.e. no internal antenna available, only RF connector). The level of the output
power setting will also affect the levels of the harmonics as can be seen in Table 3.
Refer to Table 5, to summarize all the previous mentioned application variables to obtain the
recommended application settings. The recommended power setting is also included in Table
5.
10 dBm
0 dBm
10 dBm
0 dBm
ETSI Internal Antenna
JTI with LC
0xC0: 10.8 dBm
JTI no LC
0x50: 0.3 dBm
FCC Internal Antenna
JTI with LC
0xC0: 11.2 dBm (1)
JTI with LC
0x8E: 0.8 dBm
ETSI (RF Connector)
JTI with LC
0xC2:10 dBm
JTI no LC
0x50: 0.3 dBm
FCC (RF Connector)
JTI with LC
0xC0: 11.2 dBm
JTI with LC
0x8E: 0.8 dBm
Table 5. Recommended Output Power Settings and Application Configuration
For example; a customer with PCB size restrictions has an integrated antenna [7], 0 dBm
output power; targeting only the ETSI market. With reference to Table 5; the LC filter will not
be required for regulatory issues and with a power setting of 0x50, the expected power
should be around 0.3 dBm.
Good practice would be to incorporate the LC filter into the first prototype. The filter can
always be removed by using a 100 pF capacitor or 0 ohm resistor instead of using the 5.6 nH
inductor and leaving the 1.8 pF capacitor un-mounted.
SWRA250A
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