2-87
RF2128
Rev A3 010112
2
Application Schematic
2450MHz
Pin
Function
Description
Interface Schematic
1VCC2
Power supply for the driver stage and interstage matching. External
matching on this pin is required to optimize the gain. The matching on
this port also greatly affects the input impedance. A decoupling capaci-
tor of 330pF is required, together with a series RC for tuning for maxi-
mum gain at the desired frequency. See the application information for
details.
2GND1
Ground connection for the driver stage. Keep traces physically short
and connect immediately to the ground plane for best performance.
3PD
Power Down control. When this pin is "low", all circuits are shut off. A
"low" is typical 1.2V or less at room temperature. When this pin is
"high", all circuits are operating normally. A "high" is VCC.IfPDisbelow
VCC, output power and performance will be degraded. This could be
used to obtain some gain control, but results are not guaranteed.
4RF IN
RF Input. This is a 50
Ω input, but the actual impedance depends on the
matching provided on pin 1. An external DC blocking capacitor is
required if this port is connected to a DC path to ground.
5GND2
Ground connection for the output stage. Keep traces physically short
and connect immediately to the ground plane for best performance.
6RF OUT
RF Output and power supply for the output stage. Bias for the output
stage needs to be provided on this pin. This can be done through a
quarter-wave microstrip that is RF grounded on the other end. For
matching to 50
Ω, an external series microstrip line is required.
7RF OUT
Same as pin 6.
8VCC1
Power supply for the bias circuits. An external RF bypass capacitor of
22pF is required. Keep the traces to the capacitor as short as possible,
and connect the capacitor immediately to the ground plane.
Pkg
Base
GND
Ground connection. The backside of the package should be connected
to the ground plane through a short path, i.e., vias under the device
may be required.
1
2
3
4
8
7
6
5
BIAS
CIRCUITS
PACKAGE BASE
1.5
Ω
2.4 pF
330 pF
22 pF
V
CC
RF IN
6.2 pF
22 pF
1nF
15 pF
RF OUT
PCB materials: FR-4
Thickness: 0.031"
VPD
POWER
DOWN
33 pF
L= 175 mil,
W= 10mil
L= 250 mil,
W= 20 mil
L = 220 mil,
W=25mil
L = quarter wave,
W= 10mil
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