including the bonding-wires effect, using
a four-port network analyzer and micro-
probes. As Figure 10 shows, we mea-
sured the previous design s insertion loss
above 10 dB at 30 GHz. A resonance
occurs even at around 23 GHz, where the
insertion loss increases up to 15 dB.
However, the proposed design s inser-
tion loss is below 3.5 dB at up to 30 GHz,
and the 3-dB frequency is higher than
20 GHz. Furthermore, there is no reso-
nance, meaning the signal does not feel
any severe discontinuity when passing
through the package. The proposed
design shows remarkably enhanced per-
formance over the previous design.
BY AVOIDING the use of low-loss dielec-
tric material or advanced packaging tech-
nology, our WB-PBGA package can provide a low-cost
packaging solution for future high-speed serial links.
Although our consideration in this article is limited to WB-
PBGA packages, we could readily apply the proposed
design methodologies to advanced packaging technolo-
gies, further improving channel bandwidth.
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Proposed design with BT-MG
Figure 8. Post-layout simulation results (a) for previous (b) and proposed
Figure 9. Photographs of assembled package and board (die
is not shown): previous design (a), and proposed design (b).
Figure 10. Comparison of measured results for overall