Power System-on-Chip for Future Airborne Sensor Systems
Typ
Examensarbete för masterexamen
Program
Wireless, photonics and space engineering (MPWPS), MSc
Publicerad
2019
Författare
Bjärehäll, Emil
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
This thesis looks into the requirements on technology to realize a fully integrated
GaN power System-on-Chip for a switched mode DC-to-DC converter that could
be used in future airborne sensor systems. A fully integrated power stage would
save much space and weight, which is beneficial in any application and, especially,
for airborne applications. The topologies considered include conventional Buck-type
converters, interleaved Buck converters and switched capacitor converters. The target
input voltage is 270V and the power stage conversion ratio is 10-to-1. Focusing
primarily on optimizing steady state efficiency the necessary integrated passive components
are designed and simulated. It is identified that an advanced technology
for multi-layered or very thick conductors is a requirement, and based upon these
two new inductor topologies are proposed. The multi-layered inductors utilize two
coupled layers of 5 μm thick spiral conductors and the very thick inductors use a
single conductor layer with a 30 μm conductor. A simple linear model is also presented
to describe the most important performance characteristics for commercial
GaN devices, the correlation between parasitic drain-source capacitance and the
maximum tolerated drain-source voltage and current. Finally, complete power stage
design examples are presented alongside approximate on-chip area requirements for
the analyzed active and passive components. The performance of the designs are
verified with simulations and the multi-layered inductors provide power stages with
optimum efficiencies of 46% to 65% at switching frequencies in the 70 to 150MHz
range. The very thick inductors reach efficiencies of 61% to 71% operating at 40 to
80MHz.