Preliminary
4-33
RF2048
Rev A5 010110
4
Application Schematic
Pin
Function
Description
Interface Schematic
1RF IN
RF input pin. This pin is NOT internally DC blocked. A DC blocking
capacitor, suitable for the frequency of operation, should be used in
most applications. DC coupling of the input is not allowed, because this
will override the internal feedback loop and cause temperature instabil-
ity.
2GND
Ground connection. Keep traces physically short and connect immedi-
ately to ground plane for best performance.
3RF OUT
RF output and bias pin. Biasing is accomplished with an external series
resistor and choke inductor to VCC. The resistor is selected to set the
DC current into this pin to a desired level. The resistor value is deter-
mined by the following equation:
Care should also be taken in the resistor selection to ensure that the
current into the part never exceeds 75 mA over the planned oper-
ating temperature. This means that a resistor between the supply and
this pin is always required, even if a supply near 3.6V is available, to
provide DC feedback to prevent thermal runaway. Because DC is
present on this pin, a DC blocking capacitor, suitable for the frequency
of operation, should be used in most applications. The supply side of
the bias network should also be well bypassed.
4GND
Same as pin 2.
R
V
SUPPL Y
V
DEVI CE
–
()
I
CC
-------------------------------------------------------
=
RF OUT
RF IN
RFOUT
22 pF
R
BIAS
10 nF
22 pF
47 nH
22 pF
RF IN
V
CC
13
2
4
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