Northrop Grumman has been awarded a contract by the Defense Advanced Research Projects Agency (DARPA) to develop more efficient radio frequency (RF) transmitter technology through the Microscale Power Conversion program.

Under the three-year, $8.9 million contract, Northrop Grumman will conduct research on high-efficiency transmitters with gallium nitride (GaN) Class E power amplifiers in conjunction with RF wideband contour modulation and sub-banded switching supply modulation.

The objective of the program is to develop innovative RF power amplifier designs that incorporate supply modulation and control enabled by novel power switch technology.

The key to this research is to broaden the RF power amplifier's supply modulation bandwidth up to 500 MHz with composite efficiency of no less than 75 percent by employing the contour modulation to maintain efficiency performance of the amplifier.

Contour modulation is a technique in which a phase-modulated signal waveform and amplifier output impedance work together to maintain higher efficiency over a sizable output power back-off.

When supply modulation and contour modulation are working in concert, the dynamic range and efficiency of the power amplifier can be further improved. Microscale integration and packaging with thermal design considerations is critical in achieving the efficiency.

"With more innovative RF power amplifier designs, we can produce much more efficient RF transmitters without increasing their size," said Pat Antkowiak, vice president and general manager of Northrop Grumman's Advanced Concepts and Technologies Division.

"This technique can open the door to creating more powerful electronic systems for a wide variety of applications."

The design work will be performed by Northrop Grumman and its subcontractors, the University of California at Los Angeles (UCLA) and TriQuint Semiconductor.

The final integration and demonstration will be done by Northrop Grumman in Linthicum. UCLA will work on system architecture and co-design, design of the Complementary Metal Oxide Semiconductor circuit and other elements, controls and test support. TriQuint Semiconductor will work on GaN and related process technologies.