Transcript RF & AMS Technologies for Wireless Communications

RF & AMS Technologies for
Wireless Communications
Introduction
Present the challenges of RF and AMS
technology for wireless applications
operating between .8 GHz – 100 GHz in
Cellular Phones
Wireless LAN
Wireless personal area network
Phased array RF systems
And other wireless applications
Current Area of Research
Frequency (RF) region between 10 GHz –
40 GHz is the region where competition is
Group IV semiconductors (Si & SiGe)
dominate below 10 GHz
Group III-V semiconductors dominate
above 40 GHz
Why the Gap?
SiGe can operate between 10-40 Gbits
range
However, it does not perform well when
either high power gain or ultra low noise is
required
SiGe and GaAs is currently being used
between 10 GHz – 40 GHz
These are WLAN, Satellite TV, UWB,
LMDS
Performance
Performance increases in following order:
Si CMOS, SiGe, GaAs, InP metamorphic
Two or more technologies coexist with one
another for following applications
Cellular transceivers, modules for terminal
power amplifiers, millimeter wave
receivers
Current trends
BiCMOS is mostly used in cellular
transceivers in place of CMOS
GaAs HBT and LDMOS devices are used
in modules for terminal power amplifiers
GaAs PHEMT and InP HEMT is used in
mm-wave receivers
Important parameters for
Wireless Systems
Cost
Available frequency band
Power consumption
Functionality
Size of mobile units
Appropriate performance requirements
Protocols & Standards

Operating Frequencies, channel bandwidth and
power
How to increase RF performance?
For silicon by geometrical scaling
For III-V compound semiconductors by
optimizing carrier transport properties
through materials and bandgap
engineering
Four Distinct Wireless system
building blocks
Analog/mixed-signal (Nick)
RF Transceivers (Nick)
Power amplifiers & Power management
Millimeter Wave
Power Amplifiers and Power
Management
High voltage devices are used in base
station power amplifiers such as
Si LDMOS, GaAs FET, GaAs PHEMT,
SiC Fet, GaN FET
Migrating away from packaged single die
with RFICs to multi-band multi-mode
integrated modules – deliver a complete
amplifier solution
Power Amplifiers and Power
Management
These modules integrate most of the matching
and bypassing networks and provide power
detection, power management, filtering and RF
switches for both transmit/receive and band
selection
Signal isolation becomes difficult due to high RF
voltage created by the power amplifiers and
power management circuit, and internally
generated frequencies which prevents full SOC
implementation
Millimeter Wave
Compound semiconductors dominate the
10-100 GHz range
HEMT, PHEMT, and MHEMT are used for
analog mm-wave applications
Great diversity in the nature and
performance of these devices due to
selection of materials, thickness and
doping in the stack
Millimeter Wave
Performance trends driven by bandgap
engineering of the epitaxial layer stack in
concern with shrinking lithography
Major performance metrics – noise, power,
efficiency, breakdown and lithography
dimensions
This sub-section has greatest diversity in
combinations of materials, device types,
applications and performance
Millimeter Wave
Six-inch GaAs wafers are becoming de
facto standard
GaAs tends to be two generations behind
Si in wafer size
Thermal dissipation for high power III-V
devices is one of the critical challenges,
especially true for high-power density
devices such as GaN
Questions?