Medical Design Briefs - November 2021 - 38

and the researchers gathering information.
" The
virtual prompts have proven to be
very helpful, " Yeo says. " They speed up
and improve user engagement and accuracy.
And we were able to record continuous,
high-quality motor imagery activity. "
According to Mahmood, future work
on the system will focus on optimizing
electrode placement and more ad -
vanced integration of stimulus-based
EEG, using what they've learned from
the last two studies.
This research was supported by the
National Institutes of Health (NIH
R21AG064309), the Center Grant
(Hu man-Centric Interfaces and En gi -
neer ing) at Georgia Tech, the
National Research Foundation of
Korea (NRF-2018M3A7B4071109 and
NRF-2019R1A2C2086085), and Yonsei -
KIST Convergence Research Program.
Georgia Tech has a pending patent
application related to the work
described in this paper.
Citation: Musa Mahmood, et al.,
" Wireless Soft Scalp Electronics and
Virtual Reality System for Motor Imagerybased
Brain-Machine Interfaces. " (Ad -
vanced Science, July 2021)
This article was written by Jerry Grillo,
Georgia Tech. For more information, visit
www.me.gatech.edu.
New Isolated Power Supply Chip Design Improves Efficiency
The new design
improves the
conversion
efficiency and
power density of
the chip.
University of
Science and
Technology
Hefei, China
A research group led by
Prof. Cheng Lin from the
School of Microelec -
tronics at the Uni versity
of Science and Tech -
nology of China has made
significant achievements
in the field of fully integrated
isolated power
chip design. The research
group proposed a power
supply chip based on a
glass fan-out wafer-level
package (FOWLP), achiev -
Form factor
& Cost
SOIC
Tx
TF
Rx
Tx
BGA
Tx
Flip-chip
Water
level
(Proposed)
Tx TIP Rx
TF
Rx
RDL 1
RDL 1
TF
Rx
Fan-out area
PAD
Solder ball
RDL 1
Challenges: large form factor
high cost
Tx Chip
low power density
Transformer in package
Secondary coil
Primary Coil
Glass
Rx Chip
Height 78 ∼µm
Polyimide
Solution: Proposed TiP isolated DC-DC
PCB
RDL3:Secondary coil
RDL2:Interconnections
V∞=3 ∼6v
Polyimide
Glass-based FOWLP Package
Glass TF
Tx Chip
LC Tank
Oscillator
PWM2
RDL1:Primary coil
Decoder
CMOS TF
GND1
GND2
VPULSE
Encoder
PWM1
PWM
Control
LP
LS
Rectifier
Rx Chip
VISO =3.3/5V
POUTmax =1.25W
The fully integrated isolated power chip. (Credit: Pan Dongfang)
ing 46.5 percent peak transformation
efficiency and 50 mW/mm2
density.
Tx Chip
Top
View
Compared with a traditional isolated
power
Rx Chip
power supply chip, this new chip
design interconnects the receiving and
transmitting chips through the
microtransformer made of the
rewiring layer, showing no need of
additional transformer chips. In
this way,
it lowered the need for
three or even four chips in the
existing
chip design,
800 µm
Oscillator
LC Tank
Bottom
View
Decoder
BIAS
BIAS
Decoder
1200 µm
Rectifier
BIAS
BIAS
PWM
Control
Encoder
The isolated power system package and chip. (Credit:
Pan Dongfang)
38
PWM
Control
improving the efficiency of isolated
power supply.
In addition, the researchers proposed
a grid voltage control technology
with a variable capacitor,
which maintains the grid peak voltage
in the best, safest voltage range
even in a wider
supply
voltage
range. The design improves the
www.medicaldesignbriefs.com
Cov
ToC
greatly
conversion efficiency and power density
of the chip effectively, providing a
new solution for the design of isolated
power chips in the future.
ter national
This work was published at IEEE In -
Solid State Circuits
Conference (ISSCC) and selected as
demo demonstration at the meeting.1
Reference
1. D. Pan et al., " 33.5 A 1.25W 46.5%-PeakEfficiency
Transformer-in-Package Isolated
DC-DC Converter Using Glass-Based FanOut
Wafer-Level Packaging Achieving
50mW/mm2 Power Density, " 2021 IEEE
International Solid-State Circuits
Conference (ISSCC), 2021, pp. 468-470,
doi: 10.1109/ISSCC42613.2021.9365955.
For more information, visit https://
english.cas.cn.
Medical Design Briefs, November 2021
Powder density
Rx chip
Tx Chip
Glass substrate
1450 µm
1450 µm
http://www.me.gatech.edu https://english.cas.cn http://www.medicaldesignbriefs.com
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