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proximately 2dBm output power over the whole band. This topology is intrinsically narrow band, since the

LC balun is tuned at a single frequency. If the application requires a different sub-band, the LC combiner

could be easily adjusted to be tuned at the frequency of interest.

Figure 24. LC lumped balun and matching network

The 6.8nH shunt inductor works as a DC feed for one of the open collector terminals as well as a matching

element along with the other components. The 1.1nH series inductors are used to resonate the parasitic

capacitance of the chip.

For an optimum output matching it is recommended to use 0402 Murata or AVX capacitors and 0403 or

0604 HQ Coilcraft inductors. It is also advisable to use short interconnection paths to minimize losses and

undesired impedance shift.

An alternative topology, which allows for a more broadband matching and balanced to unbalanced con-

version, is shown in

Figure 25.

Figure 25. Microstrip line and lumped matching network

1.1nH

3.6nH

0.3pF

6.8nH

0.7pF

50 O hm

3.6nH

0.3pF

1.1nH

0.7pF

3.5nH

2:1

W=20mil

L=500mil

W=20mil

L=500mil

W=20mil

L=300mil

W=20mil

L=300mil

C=0.4pF

C=0.8pF

C=0.8pF

L=2.2nH

L=2.2nH

VCC

VCC

RFOUTP

RFOUTN

50Ohm load