Page 210 - System on Package_ Miniaturization of the Entire System

184 Cha pte r F o u r

2.75

19

NF (in dB) Area (in mm 2 )

16

2.25
50 55 60 65 70 75 80 85 90
Q g
FIGURE 4.33 NF versus Q versus area.

As an example of the chip-package codesign methodology discussed so far, an LNA
for GSM applications is designed for the 0.5 μm CMOS technology, with a standard
source resistance of 50 Ω and an operating frequency of 1.9 GHz, leading to inductance
values of 9 and 1.2 nH for L and L , respectively. The parameter L is small enough to be
g
s
s
implemented on-chip; however, L is too high to be implemented on-chip without a
g
drastic increase in the NF of the circuit.
Plotting the NF of the LNA versus its gate inductor Q, the NF decreases from about
5.2 to 2.1 dB as the Q of the gate inductor is increased from 10 to 200. However, on
designing, fabricating, and measuring different topologies for the gate inductance
(on the organic substrate mentioned previously), it is found that its size increased from
2
2
9 mm for a Q of 110 to 28 mm for a Q of 170. Since the NF of the LNA is not affected by
an increase in Q beyond 70 to 90 and since size constraints limit the packaged device to
g
an area of 3.5 mm × 3.5 mm, the inductor that provides the optimum Q for a minimum
size is chosen.
Figure 4.34 shows the layout of the LNA, along with the gain and NF numbers. The
embedded inductor has a two-loop Coplanar Waveguide (CPW) topology (ground on
2
same layer as inductor), occupies ∼9 mm of area, and has a Q of 110.
4.3.2 Concurrent Oscillator Design
Many embodiments of LCP-based single-band oscillators with low phase noise and low
power consumption have been demonstrated in [45, 49–50]. However, next-generation
wireless communication radios are required to be frequency agile and need to seamlessly
span multiple bands of frequencies to cover different standards globally [51]. Such a
concurrent multiband (or multimode) system provides convergence of many standards
and enables users to communicate around the globe using only one portable device.
Current solutions to the multiband systems are not truly concurrent, in the sense that
an electronic switch is used to alternate between many frequencies. Such radio