Abstract: Presents design layout used to implement a 5GHz low-noise amplifier (LNA) based on the MAX2648. Low cost FR-4 PCB material is used.
Rapid engineering prototypes are real circuits that Maxim application
engineers have built and measured in our labs. They can provide
a starting point for new RF designs. They are not available as evaluation
kits.
A WLAN 802.11a/b/g World-Band reference design using MAX2828/9 is currently available.
Please contact the factory for more information.
The MAX2648 is a high-linearity, silicon-germanium (SiGe) low-noise amplifier
(LNA) designed for 5GHz wireless LAN systems based on 802.11a and HiperLAN2
standards. In order to achieve a low cost design, the device can be replicated
using a FR4 type substrate with coplanar waveguide traces rather than
the microstrip on Duroid used in the MAX2648 EV Kit. Agilent™ ADS was utilized to model the EV Board topology into the new coplanar format.
PCB Specifications
RF Substrate Height
3.9mils
Overall Board Height
62mils nominal
Transmission Line Configurations
Grounded Coplanar Wave Guide (CPWG)
Width
7.2mils
Gap
10mils
Recommended
Input Network Line Lengths
All distances are from center to center of component
mounting pads
C10 to C11
75mils
C11 to U1
90mils
Recommended
Output Network Line Lengths
All distances are from center to center of component
mounting pads except where noted
U1 to L1
45mils (center of U1 output pad to edge of L1 pad)
L1 to C13
154mils
C13 to C15
21mils
While the measured performance of the MAX2648 on a low-cost substrate
is nearly equivalent to the performance of the MAX2648 EVKit, there is
a slight degradation of the noise figure due to the higher loss of FR4
material:
Measured loss of EV Kit PCB using Roger's 4350
0.5dB
Measured loss of PCB using FR4
1.2dB
The MAX2648 provides high gain, low noise and high linearity performance.
This allows the device to be used as a first-stage LNA, and LO buffer
, or a transmitter driver amplifier. It provides 17dB gain, 1.8dB noise
figure, and 0dBm input 3rd order intercept point (IIP3) while consuming
only 12mA. It is packaged in a tiny 2 × 3 chipscale package with 6 solder
bumps, measuring 1.0mm × 1.5mm.
Figure 1.
Agilent is a trademark of Agilent Technologies, Inc.
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