MTT-S 2009: Cree Demonstrates Record Efficiency GaN HEMT Doherty Amplifier

Highlighting the performance advantages of its growing line of commercial high-power RF transistors, Cree, Inc. announces the first public demonstration of a record 50 percent efficiency Doherty transistor amplifier at the 2009 IEEE/MTT-S International Microwave Symposium being held in Boston this week.

The demonstration amplifiers combine Cree's latest 120W and 240W GaN HEMT transistors linearized with Texas Instruments' GC5325, a single-chip wideband digital pre-distortion transmit processor, to enable improved power efficiency for wireless basestation applications. The following amplifiers are being demonstrated at the Cree booth (#2418):

• A 50% efficient, 2.11 to 2.17 GHz 480 Watt peak power Doherty amplifier having greater than 80 Watts average power under a W-CDMA (6.5dB Peak/Average) corrected to better than -50dBc ACLR covering well over the 2.11 to 2.17 GHz UMTS band. This Doherty amplifier employs the new CGH21240F pre-matched 240W GaN HEMT transistor.
• A 42% efficient, 240 Watt class A/B amplifier, using the CGH21240F transistor, having 40 Watts average power under a W-CDMA (6.5dB Peak/Average) corrected to better than -50dBc ACLR covering the 1.8 to 2.3 GHz operating bandwidth.
• A 35% efficient, 870MHz 120 Watt class A/B amplifier, using the new CGH09120F transistor, having 20 Watts average power under a two carrier W-CDMA (7.5dB Peak/Average) signal corrected to better than -50dBc ACLR covering 25% instantaneous bandwidth. This same transistor has been demonstrated in a number of other amplifier applications in the range of 700 to 1800 MHz including DVB-H (digital video broadcast).

Texas Instruments' GC5325 combines a crest factor reduction block (CFR) and a digital pre-distortion block (DPD) to improve power amplifier (PA) efficiencies. A system evaluation kit is also available including the GC5325, a floating-point DSP, high-speed data converters and amplifiers, clocking and RF components to allow for easy demonstration of these efficiencies across a variety of signals.

"We continue to demonstrate that our GaN HEMT transistors provide power, bandwidth, and efficiency not achievable with other technologies such as silicon and gallium arsenide transistors. These demonstrations directly address the demand for higher-efficiency, broader-bandwidth HPAs in the small form factors necessary for emerging remote radio head and microcell applications. The marketing cooperation between Cree and Texas Instruments validates that high-efficiency performance coupled with excellent linearity and spectral mask compliance is possible with our current line of commercial products," said Jim Milligan, Cree director of RF and microwave products.

About Cree
Cree is a market-leading innovator of semiconductor solutions for wireless and power applications, lighting-class LEDs, and LED lighting solutions.

Cree's product families include power-switching devices and radio-frequency/wireless devices, blue and green LED chips, high-brightness LEDs, lighting-class power LEDs, and LED fixtures and bulbs. Cree solutions are driving improvements in applications such as variable-speed motors, wireless communications, general illumination, backlighting and electronic signs and signals.

For more information, visit: www.cree.com

SOURCE: Cree, Inc.