ATA8201_09 Datasheet, PDF (12/44 Pages) ATMEL Corporation – UHF ASK/FSK Receiver

2.5 Blocking, Selectivity
As can be seen in Figure 2-6 on page 12, and Figure 2-7 and Figure 2-8 on page 13, the
receiver can receive signals 3 dB higher than the sensitivity level in the presence of large block-
ers of –34.5 dBm or –28 dBm with small frequency offsets of ±3 MHz or ±20 MHz.
Figure 2-6, and Figure 2-7 on page 12 show the narrow-band blocking, and Figure 2-8 on page
13 shows the wide-band blocking characteristic. The measurements were done with a useful
signal of 315 MHz, FSK, 10 Kbits/s, ±38 kHz, Manchester, BR_Range2 with a level of
–105 dBm + 3 dB = –102 dBm, which is 3 dB above the sensitivity level. The figures show how
much larger than –102 dBm a continuous wave signal can be, until the BER is higher than 10^–3.
The measurements were done at the 50Ω input shown in Figure 2-1 on page 7. At 3 MHz, for
example, the blocker can be 67.5 dBC higher than –102 dBm, or
–102 dBm + 67.5 dBC = –34.5 dBm.
Figure 2-6.
Close-in 3-dB Blocking Characteristic and Image Response at 315 MHz
70.0
60.0
50.0
40.0
30.0
20.0
10.0
0.0
-10.0
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
Distance from Interfering to Receiving Signal (MHz)
Figure 2-7. Narrow-band 3-dB Blocking Characteristic at 315 MHz
80.0
70.0
60.0
50.0
40.0
30.0
20.0
10.0
0.0
-10.0
-5.0
-4.0
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
4.0
5.0
Distance from Interfering to Receiving Signal (MHz)
12 ATA8201/ATA8202
4971C–INDCO–04/09