Cost-Effective GaAs Read IMPACT Transmitters.
Abstract
The objective of this program is to develop a low-cost 5-GHz 40-W FM CW transmitter, using GaAs Read IMPATT diodes as RF power-generating elements, suitable for data-link applications. Results of work so far indicate that the RF performance goals for the transmitter can be achieved, but that size, weight, and primary power consumption goals will be exceeded. We have designed a transmitter system that separates the unit into four main subassemblies: a VCO-driver, a multidiode output stage, a multichannel current regulator, and a DC-to-DC inverter. The VCO-driver, producing 3.3-W output at 5 GHz, has been assembled and tested. Epitaxial wafers for the high-power GaAs Read diodes to be used in the output stage have been successfully grown. The best diode result obtained so far is 21-W CW output at 4.86 GHz with 29.5 percent efficiency, and five of six wafers processed have produced 15-W diodes. The diodes permit a four-diode output stage. Six monthly shipments of six diodes representative of those to be used in the output stage have been made to RADC. The ourput stage design uses a nonresonant parallel-type power combiner based on the modified Wilkinson hybrid described by Gysel. Four single-diode oscillator modules are coupled to this combiner. The combiner and modules are realized in trapped inverted microstrip (TIM) line. Basic TIM-line test circuits have been assembled and are awaiting evaluation. A resonant-cavity power combiner design is also available for possible use as an output stage. The circuit design for the multichannel current regulator is complete.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1977
- Accession Number
- ADA044034
Entities
People
- R. N. Wallace
Organizations
- RTX