AN4356 Datasheet, PDF (10/14 Pages) STMicroelectronics – Antenna desense on handheld equipment

Solution to avoid antenna desense
AN4356
Let us see the benefit of these solutions on the USB example shown at the beginning of this
note. Figure 14 and Figure 15 summarizes the results obtained in P-GSM 900 band and
WCDMA band VIII.
Figure 14. Effect of filtering during USB activity on TIS results in P-GSM 900 band
935.2 MHz
-80
947.4 MHz
959.8 MHz
-90
-100
-110
-120
No USB traffic
P-GSM 900
USB traffic without ECMF
USB traffic with ECMF
Figure 15. Effect of filtering during USB activity on TIS results in WCDMA (band VIII)
927.4 MHz
-80
-90
942.4 MHz
957.6 MHz
Disqualified
-100
Qualified
-110
WCDMA Band VIII
-120
No USB traffic
USB traffic without ECMF
USB traffic with ECMF
The ECMF improves the TIS in each band up to -7 dBm. If the minimum sensitivity required
is -103 dBm, 70% of the bands are recovered.
10/14
DocID025260 Rev 1