Figure 2. MAX2265 Typical Application Circuit
each device; suggested component values, suppliers,
and part numbers are listed in Table 1. These values
are optimized for best simultaneous efficiency and
return loss performance. Use high-quality components
in these matching circuits for greatest efficiency.
Layout and Power-Supply Bypassing
A properly designed PC board is essential to any
RF/microwave circuit. Be sure to use controlled imped-
ance lines on all high-frequency inputs and outputs.
Proper grounding of the GND pins is fundamental; if the
PC board uses a topside RF ground, connect all GND
pins (especially the TSSOP package exposed GND pad)
directly to it. On boards where the ground plane is not on
the component side, it’s best to connect all GND pins to
the ground plane with plated through-holes close to the
package.
To minimize coupling between different sections of the
system, the ideal power-supply layout is a star configu-
ration with a large decoupling capacitor at a central
V
CC
node. The V
CC
traces branch out from this central
node, each leading to a separate V
CC
node on the PC
board. A second bypass capacitor with low ESR at the
RF frequency of operation is located at the end of each
trace. This arrangement provides local decoupling at
the V
CC
pin.
Input and output impedance-matching networks are
very sensitive to layout-related parasitics. It is important
to keep all matching components as close to the IC as
possible to minimize the effects of stray inductance
and stray capacitance of PC board traces.
