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8-24
RF2418
Rev A7 060203
Application Schematic
High Impedance Output Configuration
850MHz
Pin
Function
Description
Interface Schematic
10
GND
Same as pin 2.
11
RF IN
Mixer RF Input port. For a 50
Ω match at 900MHz use a 15nH series
inductor. This pin is NOT internally DC-blocked. An external blocking
capacitor must be provided if the pin is connected to a device with DC
present. A DC path to ground (i.e. an inductor or resistor to ground) is,
however, acceptable at this pin. If a blocking capacitor is required, a
value of 22pF is recommended.To minimize the mixer’s noise figure, it
is recommended to have a RF bandpass filter before this input. This will
prevent the noise at the image frequency from being converted to the
IF.
12
GND
Same as pin 2.
13
GND
Same as pin 2.
14
LNA OUT
50
Ω output. Internally DC-blocked.
RF IN
LNA OUT
1
2
3
4
5
6
7
14
13
12
11
10
9
8
LNA
MIXER
BUFFER
10pF
RF AMP
IF Filter, Hi Z
IF OUT
RF IN
Image Filter 50
Ω
10 nH
LO IN
V
DD
V
DD
L1 and C1 are picked to match the mixer's output impedance (4 k
Ω II 10 pF) to the IF
filter's impedance, at the IF frequency. C1 also serves as a DC block, in case the IF filter
is not an open circuit at DC.
L1
100 nF
C1
47 pF
100 nF
10 nH
4 pF
1 nF
15 nH
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