FX909A 参数 Datasheet PDF下载

Wireless Modem Data Pump

FX909A

Suitable values being:

8000 bits/sec

4800 bits/sec

R4

100k

100k

C5

430pF

710pF

The signal at the TXOP pin is centred around V

BIAS

and is approx 0.2 x V

DD

pk-pk, going positive for

a logic '1' and negative for a logic '0', if the modem is not inverting the Tx data.

A capacitor may be fitted if ac coupling of the input to the frequency modulator is desired, see section

1.6.4.

The 'eye' diagram of the transmitted signal (after the external R4/C5 network) is shown in Figure 5.

Figure 4 Typical Tx Filter Frequency Response (after the external RC filter)

Figure 5 Transmitted Signal Eye Diagram (after the external RC filter)

©

1996 Consumer Microcircuits Limited

9

D/909A/4