2
Circuit Description
The circuit schematic and assembly drawing are shown on the last two pages.
Matching Circuits
The output matching is mainly through L3 and it should be placed close to the device.
The input matching consists of L1 and C2, and C1 is used for DC block For applications where
noise figure is critically important, a high Q inductor, such as wire-wound type, is recommended
over regular chip inductor for L1. Using high Q inductors can improve the noise figure by about
0.05dB. The values of L1 and C2 used on this evaluation circuit are chosen for a reasonable
balance between input return loss and noise figure. A further trade-off can be made between
these two parameters by adjusting the values of L1 and/or C2.
Desensitization Specifications
The desensitization data are shown in the next section for several frequency bands. This
performance spec is strongly affected by the circuit topology of the input matching network as
well as component values for given a topology. The matching circuit on this circuit is chosen for
its relative simplicity and optimal balance between noise figure and input return loss. If any
improvement on the desensitization spec is desirable at either higher or lower frequencies, a
different set of component values or a different circuit topology may be used.
PCB Material
The PCB is FR4 four layer board. The top and bottom dielectric layers are 8mil thick. The total
board thickness is 62mil.
