max2247ebct Maxim Integrated Products, Inc., max2247ebct Datasheet - Page 8

• Manufacturer Part Number: max2247ebct
• Description: Max2247 2.4ghz Sige Linear Power Amplifier
• Manufacturer: Maxim Integrated Products, Inc.

The MAX2247 is a three-stage amplifier that requires
special attention to board layout and grounding for
optimum output power, gain, efficiency, and side-lobe
suppression. For ease of implementation, the MAX2247
evaluation (EV) kit layout should be used as a model.
Gerber files are available from Maxim upon request.
Follow the recommendations below to optimize perfor-
mance when adapting the layout to your board.
V
outputs of the first- and second-stage amplifiers and
are also part of the interstage matching networks
required to optimize performance among the three
amplifier stages. The MAX2247 must have a small
amount of inductance on the V
the inductance already provided on-chip. See the
Typical Application Circuit for the lumped and discrete
component values used on the MAX2247 EV kit for opti-
mum interstage matching and RF bypassing.
2.4GHz SiGe Linear Power Amplifier
Figure 2. The MAX2247 Connected to the Current DAC of the MAX2820 for Bias Control
8
CC
_______________________________________________________________________________________
1 and V
RF OUTPUT
Interstage Matching and Bypassing
CC
2 provide DC bias to the open-collector
Applications Information
DETECTOR
POWER
MAX2247
CIRCUIT
BIAS
CC
lines in addition to
PA DRIVER
CURRENT
In addition to RF bypass capacitors on each bias line, a
global bypass capacitor of 4.7µF is necessary to filter
any noise on the supply line. Route separate V
paths from the global bypass capacitor (using a star
topology) to avoid coupling between PA stages. Use
the MAX2247 EV kit PC board layout as a guide.
The MAX2247 includes internal input matching to 50Ω, so
no external matching network is required. A DC-blocking
capacitor is required at the input to the device.
The RF_OUT port is an open-collector output that must be
pulled to V
the Typical Operating Circuit). A shunt 22pF capacitor to
ground is required at the supply side of the inductor. In
addition, a matching network is required for optimum gain,
efficiency, ACPR, and output power. The EV kit should
serve as a good starting point for your layout. However,
optimum performance is layout dependent, and some
component optimization may be required. It is important to
leave room on your board for tuning/optimization.
DAC
ZERO-IF TRANSCEIVER
MAX2820
SHUTDOWN CONTROL
CC
TX POWER DETECTOR
through an RF choke for proper biasing (see
STANDARD BASEBAND/MAC IC
RX BASEBAND I/Q
TX BASEBAND I/Q
Output Matching
Input Matching
CC
bias