Page 323 - System on Package_ Miniaturization of the Entire System

Radio Fr equency System-on-Package (RF SOP) 297

Layer 6

Layer 4
Port 1
Port 2
Layer 3

Layer 2
A A´
Layer 1

Layer 0

(a) (b)
0
Measurement
MoM simulation
−10

S 21 , dB −20

−30

−40

−50
1 1.5 2 2.5 3 3.5 4 4.5 5
Frequency, GHz
(c)
FIGURE 5.34 (a) A three-dimensional layer-by-layer view of multilayer fi lter structure. (b)
Photograph of the fabricated fi lter. (c) Simulated and measured S 21 for the fi lter.

5.4.8 Baluns
Baluns are required in a wide variety of microwave components such as balanced
mixers, push-pull amplifiers, multipliers, and phase shifters. The design of baluns and
their implementation in organic substrates were discussed in detail in Chapter 4. In this
section, the implementation of baluns in LTCC technology is discussed.
Figure 5.37 shows an example of a stripline-type multilayer balun developed on
LTCC technology [61]. Two shorted lines are placed next to an open line such that they
couple energy from the open line. Each of these lines is shorted to the ground planes
(through vias) above and below it, respectively. There is very good agreement between
the measurement and simulation as can be seen from the results shown in Figure 5.38.