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6 blocking, selectivity – Rainbow Electronics ATA5746 User Manual

Page 11

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11

4596A–RKE–05/06

ATA5745/ATA5746 [Preliminary]

2.5

RX Supply Current Versus Temperature and Supply Voltage

Table 2-7

shows the typical supply current of the receiver in Active mode versus supply voltage

and temperature with VS = VS3V_AVCC = VS5V.

2.6

Blocking, Selectivity

As can be seen in

Figure 2-6 on page 11

, and

Figure 2-7

and

Figure 2-8 on page 12

, 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

12

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 50

Ω input shown in

Figure 2-1 on page 6

. At 3 MHz, for

e x a m p l e , t h e b l o c k e r c a n b e 6 7 . 5 d B C h i g h e r t h a n – 1 0 2 d B m , o r
–102 dBm + 67.5 dBC = –34.5 dBm.

Figure 2-6.

Close-in 3-dB Blocking Characteristic and Image Response at 315 MHz

Table 2-6.

Measured Current in Active Mode ASK

VS = VS3V_AVCC = VS5V

2.7V

3.0V

3.3V

T

amb

=

–40°C

5.4 mA

5.5 mA

5.6 mA

T

amb

=

25°C

6.4 mA

6.5 mA

6.6 mA

T

amb

=

105°C

7.4 mA

7.5 mA

7.6 mA

Table 2-7.

Measured Current in Active Mode FSK

VS = VS3V_AVCC = VS5V

2.7V

3.0V

3.3V

T

amb

=

–40°C

5.6 mA

5.7 mA

5.8 mA

T

amb

=

25°C

6.6 mA

6.7 mA

6.8 mA

T

amb

=

105°C

7.6 mA

7.7 mA

7.8 mA

-10.0

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

-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)

B

lo

cki

n

g

L

evel

(

d

B

C

)