11-220
RF2945
Rev A10 000919
11
Pin
Function
Description
Interface Schematic
14
IF1 BP+
DC feedback node for the 40dB limiting amplifier strip. A 10nF bypass
capacitor from this pin to ground is required.
See pin 13.
15
IF1 BP-
Same as pin 14.
See pin 13.
16
IF1 OUT
IF output from the 40dB limiting amplifier. The IF1 OUT output presents
a nominal 330
Ω output resistance and interfaces directly to 10.7MHz
ceramic filters.
17
IF2 IN
IF input to the 60dB limiting amplifier strip. A 10nF DC blocking capaci-
tor is required on this input. The IF2 IN input presents a nominal 330
Ω
input resistance and interfaces directly to 10.7MHz ceramic filters.
18
IF2 BP+
DC feedback node for the 60dB limiting amplifier strip. A 10nF bypass
capacitor from this pin to ground is required.
See pin 17.
19
IF2 BP-
Same as pin 18.
See pin 17.
20
GND6
Ground connection for 60dB IF limiting amplifier. Keep traces physically
short and connect immediately to ground plane for best performance.
21
DEMOD IN
This pin is the input to the FM demodulator. This pin is NOT AC cou-
pled. Therefore, a DC blocking capacitor is required on this pin to avoid
shorting the demodulator input with the LC tank. A ceramic discrimina-
tor or DC blocked LC tank resonant at the IF should be connected to
this pin.
22
DATA REF
This pin is used for setting the adaptive Data Slicer DC reference level.
A capacitor from this pin to ground can be used to set the reference
level at the average DC level of the data bit stream.The DC level deter-
mines the bit decision threshold.
23
MOD IN
FM analog or digital modulation can be imparted to the VCO through
this pin. The VCO varies in accordance to the voltage level presented
to this pin. To set the deviation to a desired level, a voltage divider refer-
enced to Vcc is the recommended. This deviation is also dependent
upon the overall capacitance of the external resonant circuit.
See pin 24.
24
RESNTR+
This port is used to supply DC voltage to the VCO as well as to tune the
center frequency of the VCO. Equal value inductors should be con-
nected to this pin and pin 25 although a small imbalance can be used
to tune in the proper frequency range.
25
RESNTR-
See RESNTR+ description.
See pin 24.
26
VCO OUT
This pin is used is supply a buffered VCO output to go to the PLL chip.
This pin has a DC bias and needs to be AC coupled.
27
GND4
GND4 is the ground shared on chip by the VCO, prescaler, and PLL
electronics.
IF1 OUT
IF2 IN
330
330
60 k
Ω
60 k
Ω
IF2 BP+
IF2 BP-
DEMOD IN
10 k
Ω
V
CC
50k
Ω
DATA REF
RESNTR-
RESNTR+
4k
Ω
MOD IN
VCO OUT
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