Future devices for Information Technology
2003. 4. 4.
Songcheol Hong
Contents
Electronic Devices (processing devices)
High speed devices(digital, analog, RF)
High power devices
Memory devices
Optical Devices
QWLD, QDLD
Optical communication devices
GaN based Devices
Display
High speed devices
Digital, Analog(RF)
DSP upto Microwave frequencies
IEEE MTT Vol. 50, N0. 3, 2002 p900
Power dissipation/ MIPS
Digital circuits expands to Analog domain
Trends in Transmitter Architecture(Mobile)
DC-DC
converter
80
Vector
Modulator
High Speed
DSP (7GHz)
Average
Efficiency(%)
ACPR
(dBc)
Direct RF
Synthesis
60
-55
Digital
Predistor
40
-50
DSV
PA
20
Smart
PA
-45
0
Year
2000
Bias control
2003
2006
Supply voltage
control
2009
DSP
2012
SDR
One Chip Radio
Smart PA
Heterodyne type
Base/gate bias voltage control
GaAs based PA
Gate/base bias control
IF VGA
Up-Mixer
Iin
RFout
DAC
PA
Qin
VCO1
VCO2
Dynamic supply voltage (DSV) PA
Direct conversion
Supply Voltage Control  Dynamic Supply Control
DSP clock speed ~ 10MHz
GaAs PA + CMOS DC-DC converter
SiGe BiCMOS
Bias
Controller
Iin
Qin
RFout
DAC & ADC
controller
PA
VCO
Digital Predistorer
Digital predistorter
SiGe BiCMOS PA or CMOS switching PA
Amplitude
Iin
Qin
DAC & ADC
controller
Digital
prePhase
distorter
Bias
Controller
RFout
PA
VCO
Direct RF synthesis
Direct RF Synthesis
DSP clock speed ~ 7 GHz
CMOS Switching PA and controller
Iin
Qin
Bandpass
Delta-Sigma
Modulator
RFout
Switching
PA
DSP
Filter
Amplitude
/Ramping
Iin
Digital Phase &
Amplitude Mod.
Qin
Synthesizer/
VCO
Phase
Amplitude
Modulator
Switching
PA
RFout
High speed Power Devices
• MESFET/ HEMT
 High Efficiency / high Linearity
 Temperature stability
 Negative bias
 Develop
Enhancement FET
• MOSFET/LDMOS
 Low Efficiency
 Temperature Stability
 Single bias
•HBT
 High Efficiency / High Linearity
 Single bias
 High power density
 Bad temperature stability
 introduce Ballast R, careful bias circuit
Typical InGaP Emitter HBT
Structure
Fig. 1. A cross-section of IBM's SiGe HBT structure, which was used
to obtain a record-breaking ft value of 350 GHz. Credit: IBM.
HBT comparison
High power v.s. Digital
Power transistor (FETs)
Circuit design : Power combine : Unit transistor
HBT with Ballast R ( Via hole and Air bridge)
12 finger Rb=50
8 finger Rb=50
Power Cell
64 finger
MOS power cell
Conventional 구조
 Conventional 구조
(1) Poly gate와 drain metal의 저항이 클
것으로 예상
(2) Source metal이 drain metal을 덮는
구조이므로 Cds가 클것으로 예상
FET vs. HBT (size)
HBT’s (being vertical in structure) consume less die area than an equivalent FET
based production technology
Example> take a PA line-up for GSM (Pout=35dBm, Vbat=3.2V)
Ballasting
• HBT devices must be BALLASTED to ensure thermal stability
• Thermal run-away is avoided if a sufficiently large ballast resistance is placed
in either the emitter or the base of the HBT
• In a multi-finger array, one device may be hotter than other. The hotter device
will experience a drop in Vbe (-2mV/oC) which will cause it to draw even more
current from a fixed-base-voltage supply… thus it will get even hotter. The end
result is finger burn-out
Ballasting (conti…)
• Three methods are available to ballast your circuit
HBT bias circuit
• Diode-bias and current-mirror circuits can be seen here:
• The key differences are:
- Diode bias requires the diode to draw current, which can be significant
- Current mirror does not track as well over temperature
- Current mirror has the “2  Vbe” reference-voltage issue
CMOS and LDMOS power TR
IEEE EDL, Vol. 21, No.2, p81, YueTan et al.
High power LDMOS
1.
2.
3.
4.
5.
6.
7.
8.
Conclusions I High speed digital and analog devices
Submicron CMOS(0.18um) is
covering upto 10Gbps and 10GHz range.
Submicron CMOS(0.05um) will be
covering upto 40 Gbps and 40 Ghz range.
Digital part will dominate Analog and RF
Finally, only power amp in RF with digital control
will survive
LDMOS+CMOS will be a winner in Power applications
SiGe may be used in high speed digital and
10-60 GHz range RF.
GaAs HBT is used in Power and Low noise application
1- 40 GHz
InP HBT and HEMT are used
in high frequencies(above 30Ghz)
DRAM
Figure 7.4: Simplified DRAM
schematic.
DRAM design rule
Figure 7.7: Vertical stacked capacitor: Top - SEM
photograph of the storage plate. Bottom - Solid
model and grid of the simulated structure (only
the material POLY1 is displayed).
Figure 7.6: Process flow of the vertical
stacked capacitor.
FINFET
Nono MOSFET
Quantum Dot Flash memory
FRAM
Figure 1. Schematic cross section of a FRAM unit cell [1T/1C]
Conclusion II Memory
DRAM:
Design rule becomes smaller,
Ferroelectric Materials make C smaller,
New Structures
Nonvolatile Memory:
Flash Nano-flash, QD flash
FRAM
MRAM
QWLD, QDLD
Self-assembled QDs
AFM image of QD
Quantum wire grown on V groove
Figure 2. TEM micrograph showing the core of a 5-QWR La
The wires are positioned inside the 2D optical waveguide in
asymmetric configuration in order to maximize the overlap o
the optical mode with
LD, VCSEL, LED
VCSEL
Why Blue? GaN ?
LD, LED ---Conclusion III
Laser diode
QW
QD ---- High power LD
VCSEL
QW
QD ---- Low threshold Current
Blue light sources --- GaN
Storage
illumination
Standard & Applications
Optical communication devices
Expected 10 Gigabit Ethernet solution
Distance
Fiber
Solution
100m
installed MMF
300m
new MMF
850-nm VCSEL on new MMF
No solution for installed MMF
2Km
SMF
Uncooled 1300-nm FP laser
10km
SMF
Uncooled, Isolated 1300-nm DFB
40km
SMF
Traditional telecom-style cooled Isolated, externally
modulated DFB
No solution.
(FP laser can go 65m)
Method to overcome limit
 42.5 Gb/s WWDM with installed MMF & SMF
 10 Gb/s TDM with SMF & 1300nm LD
Ref.) Tutorials, Agilent, 2000 OE conference
Material property of electrical device
Property of GaAs/InP HEMT at TRW
Ref) TRW and Velocium, 2002 IEEE MTT-S workshop.
Material property of electrical device
Property of Si/GaAs/InP HBT
Ge
Si
GaAs
InP
e- mobility (cm2/V-s)
3900
1400
8500
5400
h+ mobility (cm2/V-s)
1900
450
400
200
Bandgap (eV)
0.66
1.12
1.42
1.34
Thermal Cond(W/cm-C)
0.58
1.30
0.55
0.68
BVCEO vs. Ft
Ref) Inphi inc., 2002 IEEE MTT-S workshop.
TRW and Velocium, 2002 IEEE MTT-S workshop.
Optical Rx & Tx
Digital & Analog IC
Ref) NTT., 2002 IEEE MTT-S workshop.
Optical Rx & Tx
Which technology is used
PD
Pre-amp
post-amp
155Mbps
InP
622Mbps
InP
Si BJT
2.5Gbps
InP
SiGe/GaAs
10Gbps
InP
40Gbps
CDR
DeMUX
MUX
LD-Driver
CMOS
CMOS
SiGe/GaAs
InP
InP/GaAs
Si BJT
CMOS
Si / SiGe
InP/GaAs
InP/GaAs
HEMT
Si/SiGe
HEMT
InP/GaAs
InP/GaAs
Electrical package
High speed modules (40 Gbps)
40 Gbps MUX/DeMUX
1:4 DeMUX
4:1 MUX
With InP HBT, GPPO connector
40 Gbps CDR+DeMUX
Clock Data Recovery
1:16 DeMUX
With SiGe HBT, Ball Gray package
Inphi inc., 2002 IEEE MTT-S workshop.
AMCC., 2002 IEEE MTT-S workshop.
Fig. 2. A 100 Gbit/s selector IC fabricated using InP-based
HEMT technology. Credit: NTT.
Electrical package
High speed modules( > 40 Gbps)
Aluminum Nitride package of NTT
Si MEMS of SOPHIA wireless
Monolithic Integration
AGERE SYSTEM
Tunable EML Module
- SOA Integrated
- 2-Section DBR
- Front PD Integrated
Fig. 1. Photoreceivers fabricated using hybrid manufacturing (a)
and ELT integration (b).
40Gbps modules in NTT
Waveguide type PIN-TIA
Near Field Diameter : 2 mm
The total coupled CPW lines :
characteristic impedence of 50 ohm
WG-PD Chip
CPW line
Front end IC Chip
V-Connector
Ceramic CPW
Responsivity : 0.84 ~ 0.95 A/W
by two Aspherical lenses
Cavity Resonance in PKG Housing
Optical Communication Devices --Conclusion IV
LD + Modulator
High speed VCSEL array
WDM
PD+TIA integration
TIA and LD/Modulator Drive
Optical chip set
GaN applications
Fig. 1. GaN-on-silicon platform technology offers a broad range
of applications, including microelectronic and optoelectronic
products, optical sensors and high-voltage rectifiers
AlGaN/GaN HEMTs
<< Back
Figure
1 to article
Fig. 1. A typical layer structure used for the fabrication of
AlGaN/GaN HEMTs
Fig. 3. Power performance of a 0.36 mm wide AlGaN/GaN FET
at 30 GHz, showing 2.3 W output power, 38% PAE and 8.8 dB
gain. Credit: NEC.
High power Transistor– base station amplifier
Fig. 2. Comparison of the potential power delivered by HEMTs
that have been fabricated in GaAs, SiC and GaN.
High power/speed devices Conclusion V
LDMOS
MESFET
SiC MESFET/MOSFET
GaN HEMT
Display devices --- Organic LED
Conclusion-VI
Display
LCD
OLED
CRT
Plasma
Projection
LED
Conclusions
Conclusion I --- high speed digital analog
Conclusion II --- high density memory
Conclusion III ---LD,LED
Conclusion IV ---Optical communication device
Conclusion V --- high voltage
Conclusion VI--- dispaly