LMH2110 Datasheet, PDF (27/33 Pages) National Semiconductor (TI) – 8 GHz Logarithmic RMS Power Detector with 45 dB Dynamic Range

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LMH2110
SNWS022C – JANUARY 2010 – REVISED MARCH 2013
1.5
1.0
W-CDMA, REL8
0.5
0.0
W-CDMA, REL6
-0.5
W-CDMA, REL7
-1.0
-1.5
-40 -30 -20 -10
0
10
RF INPUT POWER (dBm)
Figure 58. Variation due to Modulation for W-CDMA
Layout Recommendations
As with any other RF device, careful attention must me paid to the board layout. If the board layout isn’t properly
designed, performance might be less then can be expected for the application.
The LMH2110 is designed to be used in RF applications, having a characteristic impedance of 50Ω. To achieve
this impedance, the input of the LMH2110 needs to be connected via a 50Ω transmission line. Transmission lines
can be created on PCBs using microstrip or (grounded) coplanar waveguide (GCPW) configurations.
In order to minimize injection of RF interference into the LMH2110 through the supply lines, the PCB traces for
V_DD and GND should be minimized for RF signals. This can be done by placing a small decoupling capacitor
between the V_DD and GND. It should be placed as close as possible to the V_DD and GND pins of the LMH2110.
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