Rainbow Electronics AT86RF211 - Manual (Page 13)

13
AT86RF211
1942C–WIRE–06/02
Figure 13. IF1 Filtering
Figure 14. Schematic Input of IF1 Amplifier
Figure 15. Schematic Output of the Second Mixer
IF2 Filtering and Gain IF2 filtering achieves a narrow channel selection. In case it is not used, it should be
replaced by a > 1 nF coupling capacitor, thus the IF1 filter is the only part achieving the
channel selection. Available commercial filters with a 35 kHz BW allow data rates up to
19.6 kbps if crystal temperature drifts are very low.
For faster communications and/or wider channelization, this ceramic filter can be
replaced by an LC band-pass filter as proposed hereafter.
IF1IN
(pin 35)
330 Ω
IF1
"or"
C > 100 pF
330 Ω
IF1OUT
(pin 36)
Filter
IF1DEC
20 k Ω
330 Ω
IF1IN
1600 Ω
IF2OUT