10-43
RF2637
Rev A3 040511
Pin
Function
Description
Interface Schematic
1IN+
CDMA balanced input pin. This pin is internally DC-biased and should
be DC-blocked if connected to a device with a DC level other than VCC
present. A DC to connection to VCC is acceptable. For single-ended
input operation, one pin is used as an input and the other CDMA input
is AC-coupled to ground. The balanced input impedance is 1k
Ω, while
the single-ended input impedance is 500
Ω.
2IN-
Same as pin 2, except complementary input.
See pin 1.
3GND
Ground connection. For best performance, keep traces physically short
and connect immediately to ground plane.
4GC
Analog gain adjustment for all amplifiers. Valid control ranges are from
0V to 2.5V. Maximum gain is selected with 2.5V. Minimum gain is
selected with 0V. These voltages are only valid for a 4.7k
Ω DC source
impedance.
5OUT-
Balanced output pin. This is an open-collector output, designed to
operate into a 250
Ω balanced load. The load sets the operating imped-
ance, but an external choke or matching inductor to VCC must also be
supplied in order to correctly bias this output. This bias inductor is typi-
cally incorporated in the matching network between the output and next
stage. Because this pin is biased to VCC, a DC-blocking capacitor must
be used if the next stage’s input has a DC path to ground.
6OUT+
Same as pin 5, except complementary output.
See pin 5.
7VCC2
Supply voltage pin. External bypassing is required. The trace length
between the pin and the bypass capacitors should be minimized. The
ground side of the bypass capacitors should connect immediately to
ground plane.
8VCC1
Same as pin 7.
See pin 7.
700
Ω
BIAS
700
Ω
CDMA-
CDMA+
23.5 k
Ω
15 k
Ω
12.7 k
Ω
V
CC
OUT-
OUT+
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