RF & AMS Technologies for Wireless Communications

1. RF & AMS Technologies for Wireless Communications

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. Four Distinct Wireless system building blocks • Analog/mixed-signal (Nick) • RF Transceivers (Nick) • Power amplifiers & Power management • Millimeter Wave

10. 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

11. 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

12. 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

13. 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

14. 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

15. Questions?