Preliminary Product Information - April 1997
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Gain vs Frequency
Saturated Power Output vs Frequency
(PIN = +14 dBm)
Power Output vs Power Input @ 2.45 GHz
Efficiency vs Power Input @ 2.45 GHz
2 6 10
Power Input, dBm
The CMM2321 is a two stage amplifier that requires
a positive and negative supply voltage for proper operation. It
is essential when turning on the device that the negative sup-
ply be applied before the positive supply. When turning the
device off, the positive supply should be removed before the
negative supply is removed.
The CMM2321 can be operated over a range of sup-
ply voltages and bias points. It is important that the maximum
power dissipation of the package be observed at all times.
Biasing A negative voltage supply is needed to bias the gates
of the 2-stage GaAs FET power amplifier. Gate 1 bias is
applied through pin 3 (Vg1) and gate 2 bias is applied through
pin 4 (Vg2). Under most operating conditions gates 1 and 2
may be tied together. The positive supply voltage is applied to
pins 5 and 6 (Vd2) and pin 7 (Vd1). The negative voltage
supply should be adjusted to achieve a drain current of 600
mA with no RF input power to obtain a P1dB of approximate-
ly 30.5 dBm.
Matching Circuits Input and output matching circuits are
required. The schematic and the PCB layout for the test board
are shown on Page 3. The matching circuits for the
CMM2321 are highlighted on the PCB layout.
A single shunt capacitor is used to match the output.
6 10 14
Power Input, dBm
Their placement and value provide tuning. Vd2 is fed through
a λ/4 trace. All other capacitors shown in the schematic are
used for decoupling.
Note: Circuit board 8251 is a multiple-use test board.
The portions of the board that are used with the CMM2321
are shown as solid traces on the board layout drawing on Page
3. The interface/conversion points in the evaluation board
schematic are shown. These connection points may not be
labeled identically on Celeritek’s PB-CMM2321 evaluation
board. Contact the factory for assistance in translating the
external match to a specific application.
Supply Ramping To obtain the necessary power ramp, sup-
ply side switching should be used. Both drain voltages should
be tied together and ramped to produce the required power vs.
1. The copper pad on the backside of the CMM2321 must be
soldered to the ground plane.
2. All 8 leads of the package must be soldered to the appropri-
ate electrical connection.
3. A large ground plane area with plated thru-holes as shown
on the PCB layout should be used as a backside connection.
Contact the factory for a copy of a manufacturing application
note containing more detailed information.
3236 Scott Boulevard, Santa Clara, California 95054
Phone: (408) 986-5060
Fax: (408) 986-5095