Transcript A 1-GHz BiCMOS RF Front-End IC

RF Power Transistors
For Mobile Applications
전기공학부 2005-21326 구찬회
C. KOO
Millimeter-wave Integrated Systems Lab.
Background
History of RF Transistors
• Many different types of RF
transistors available:
-Bipolar: Si BJTs, SiGe HBTs,
III-V HBTs
-FET: GaAs MESFETs, III-V HEMTs,
Wide Bandgap HEMTs,
Si MOSFETs
In general, signals with lower frequency can
penetrate walls better.
But antenna size varies with RF wavelength,
so low-frequency RF is not practical for
handheld devices.
In addition, frequencies of RF noises are
ranging from 50-2400 MHz, so frequencies >
3000 MHz is better.
C. KOO
Millimeter-wave Integrated Systems Lab.
Operating Frequencies of
Widely Used RF Electronics
 Most RF systems having real mass markets operate under 5 GHz.
 Cellular phones(GSM, CDMA) - 900MHz,1.8 and 1.9GHz
 Future 3G cellular phones (CDMA2000, Wideband CDMA) - 3GHz
 Advanced mobile communications
- GPS(global positioning systems) - 1.8GHz
- GPRS(general packet radio service) - 2.5GHz
 Wireless local area network (Bluetooth) - 2.4 GHz
 Collision avoidance radar used in automobiles - 77 GHz
 Microwave oven - 2.4 GHz
C. KOO
Millimeter-wave Integrated Systems Lab.
RF Transistor Figures of Merit
 Cutoff Frequency fT
Frequency at which the magnitude of
the short circuit current gain h21 rolls
off to 1 (0 dB).
 Max Frequency of Oscillation fmax
Frequency at which the unilateral
power gain U rolls off to 1 (0 dB).
 fT and fmax can be extracted from h21
and U roll off at higher frequencies at
a slope of –20 dB/dec.
• Further RF Transistor FOMs : NFmin, Pout, PAE, MAG
C. KOO
Millimeter-wave Integrated Systems Lab.
HBT (1)
C. KOO
Millimeter-wave Integrated Systems Lab.
HBT (2)
HBT Types
• GaAs HBT
• InP HBT
• SiGe HBT
Design Features
• Wide bandgap emitter
• Narrow bandgap base
• Thin base (less than 0.1 μm)
• High base doping
• GaAs-based HBT has been the most widely used HBT in RF design,
but SiGe HBT has gained popularity recently due to its superior noise performance
and its compatibility with existing Si CMOS technology.
C. KOO
Millimeter-wave Integrated Systems Lab.
HEMT (1)
HEMT: High Electron Mobility Transistor
C. KOO
Millimeter-wave Integrated Systems Lab.
HEMT (2)
HEMT Types
• AlGaAs/GaAs HEMT
• InP HEMT
• AlGaN/GaN HEMT
Design Features
• Deep sub-µm gate
• Mushroom gate
• Very short gate length
• High mobility channel layer
• Large conduction band offset 2DEG
• Importance of metamorphic HEMT (mHEMT) will continue to grow.
-The key feature of this device is an InGaAs layer grown on GaAs substrate
with an In content higher than that in GaAs pHEMT.
-The main advantge of this approach is inexpensive GaAs substrate can be
used to obtain InP HEMT like performance.
C. KOO
Millimeter-wave Integrated Systems Lab.
Power Amplifiers
for Mobile Communication Systems (1)
 Cellular PA
-Current PA : 95% with GaAs
-New Comers : SiGe PA & CMOS PA (skeptical)
-SiGe BICMOS : better for integration
better for cost (?)
(Triquint claimed that GaAs has 15% less cost)
-Issues : SoC or SoP
 Wireless LAN
-Competitive technologies same with cellular PA
-IEEE 802.11g(2.4GHz, 54Mbps) & IEEE 802.11a(5GHz, 54Mbps)
-67% of 177M PAs from GaAs in 2008 (Strategy Analytics)
 Cellular Base Stations
-90% market with LDMOS
-Competitive Technologies : GaN HFET(reliability), GaAs PHEMT
 Switch – mainly with GaAs PHEMT
C. KOO
Millimeter-wave Integrated Systems Lab.
Power Amplifiers
for Mobile Communication Systems (2)
• Wide bandgap FETs(SiC MESFET& GaN HEMT) show the highest
output power densities of all RF FETs in the frequency range
important for currentmobile communication sytems (up to 5 GHz)
• Technologies for GaN HEMTs are not yet mature,
but devices with fT and fmax exceeding 100 GHz
and very high output power densities have been demonstrated.
C. KOO
Millimeter-wave Integrated Systems Lab.
Trend of RF Transistors
 Important Trends
• Continuous increase
of the frequency limits,
i.e. fT and fmax
• Development of lowcost RF transistors for
mass onsumer markets
“InP HBT and HMET possess the best frequency performance”
But, the technology for InP-based devices is not yet mature.
These devices alsohave poorer power performance.
C. KOO
Millimeter-wave Integrated Systems Lab.
References
 RF and Microwave Power Amplifier and Transmitter TechnologiesFrederick H. Raab, Peter Asbeck, Steve Cripps, Peter B. Kenington,
Zoya B. Popovic, Nick Pothecary, John F. Sevic and Nathan O. Sokal
 F. Schwierz and J. J. Liou, Modern Microwave Transistors – Theory,
Design, and Applications, J. Wiley 2002
 L. D. Nguyen et al., Ultra-High-Speed Modulation-Doped Field-Effect
Transistors,Proc. IEEE, 80, p. 494.
 D. Halchin, M. Golio, Trends for Portable Wireless Applications,
Microwave J., Jan. 1997, p. 62
 F. Schwierz and J. J. Liou, Semiconductor Devices for RF Applications:
Evolution and Current Status, Microel. Rel. 2000.
C. KOO
Millimeter-wave Integrated Systems Lab.