11-57
RF2905
Rev B11 010516
11
Pin
Function
Description
Interface Schematic
1
RX ENABL
Enable pin for the receiver circuits. RX ENABL> 2.0V powers up all
receiver functions. RX ENABL<1.0V turns off all receiver functions
except the PLL functions and the RF mixer.
2
TX ENABL
Enables the transmitter circuits. TX ENABL>2.0V powers up all trans-
mitter functions. TX ENABL<1.0V turns off all transmitter functions
except the PLL functions.
3TX OUT
RF output pin for the transmitter electronics. TX OUT output impedance
is a low impedance when the transmitter is enabled. TX OUT is a high
impedance when the transmitter is disabled.
4GND2
Ground connection for the 40dB IF limiting amplifier and Tx PA func-
tions. Keep traces physically short and connect immediately to ground
plane for best performance.
5RX IN
RF input pin for the receiver electronics. RX IN input impedance is a
low impedance when the transmitter is enabled. RX IN is a high imped-
ance when the receiver is disabled.
6GND1
Ground connection for RF receiver functions. Keep traces physically
short and connect immediately to ground plane for best performance.
7LNA OUT
Output pin for the receiver RF low noise amplifier. This pin is an open
collector output and requires an external pull up coil to provide bias and
tune the LNA output.
8GND3
Same as pin 4.
9
MIX IN
RF input to the RF Mixer. An LC matching network between LNA OUT
and MIX IN can be used to connect the LNA output to the RF mixer
input in applications where an image filter is not needed or desired.
10
GND5
GND5 is the ground connection shared by the input stage of the trans-
mit power amplifier and the receiver RF mixer.
11
MIX OUT+
Complementary (with respect to pin 12) IF output from the RF mixer.
Interfaces directly to 10.7MHz ceramic IF filters as shown in the appli-
cation schematic. A pull-up inductor and series matching capacitor
should be used to present a 330
Ω termination impedance to the
ceramic filter. Alternately, an IF tank can be used to tailor the IF fre-
quency and bandwidth to meet the needs of a given application.
12
MIX OUT-
IF output from the RF mixer. For a balanced mixer output, pull-up induc-
tors from pin 11 and 12 to VCC and a capacitor between the pins should
be used. The sum of the total pull-up inductance should be used to res-
onate the capacitor between pins 11 and 12. DC blocking capacitors of
10nF can then be used to connect the balanced output to IF1 IN+ (pin
13) and IF1 IN- (pin 14).
See pin 11.
50 k
Ω
RX ENABL
40 k
Ω
20 k
Ω
TX ENABL
TX OUT
20
V
CC
RX IN
500
LNA OUT
V
CC
GND5
MIX IN
MIX OUT-
MIX OUT+
15 pF
15 pF
GND5
GND5
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