MAX-M10S - Integration manual
Figure 26: MAX-M10S out-of-band immunity level at 400 - 1460 MHz and 1710 - 3300 MHz for the low-gain mode
(default).
shows tabulated values for out-of-band immunity at selected cellular and Wi-Fi
frequencies.
Parameter
Frequency (MHz)
699
785
915
1710
1880
1980
2350
2440
2690
Immunity level (dBm)
-15
-35
-17
-25
-25
-25
-18
-18
-18
Table 30: MAX-M10S out-of-band immunity for the low-gain mode at selected frequencies.
3.3.3 Out-of-band rejection
RF interference is typically first coupled into the antenna and subsequently conducted into the
receiver input. Typical out-of-band interference sources include transmitting antennas of other
radio systems.
Estimation of the RF interference level coupled into the receiver antenna is a starting point for
RF front-end design. For designs with other radio systems, the maximum power coupled into the
antenna can be estimated from the maximum transmission power and the isolation between the
antennas. Practical values for antenna isolation can range from 15 - 20 dB down to 6 - 10 dB for very
small devices. RF interference may also couple from external sources such as nearby mobile devices
or base stations.
A simplified test board can be used to estimate the isolation between two antennas. The
size of the board and the placement of the antennas must match the final design. Connect
the RF cables to the antenna inputs and measure S21 over the frequency band of interest
with a vector network analyzer (VNA).
The required out-of-band rejection or isolation is the difference of the maximum power coupled into
the antenna input terminal and the immunity level of the receiver RF input. The required isolation
is realized with appropriate filtering, typically with one or two SAW filters. Amplification on the RF
path reduces the out-of-band rejection and needs to be considered in filter selection. The type and
number of filters are selected based on the estimated interference level and the immunity of the
receiver.
UBX-20053088 - R03
3 Hardware integration
Page 68 of 89
C1-Public
