RF

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RF AMS Technologies for Wireless Communications
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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

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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

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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

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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

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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

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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

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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

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Four Distinct Wireless system building blocks

• Analog/mixed-signal (Nick)
• RF Transceivers (Nick)
• Power amplifiers Power management
• Millimeter Wave

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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

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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

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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

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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

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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

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• Questions?