Common-Base vs. Common-Emitter Performance and Reliability for VHF Stages

摘要

Two broadband amplifier chains were developed for operation with a minimum output power of 10watts over the 225- to 400-megahertz band. Four stages were used in each chain, with each stage having 50-ohm input and output terminals. The stages in one amplifier chain operated in the common-base configuration; the other chain used common-emitter stages. Comparison of the rf performance of the two amplifier chains showed that common-base amplifiers provided a flatter output response, a higher power gain, and a lower input VSWR than common-emitter amplifiers. Infrared scanning performed on the output stages indicated that the common-base amplifier also had a lower junction spot temperature. In high-power common-base operation, extremely low base-lead inductance was necessary to prevent the amplifier from becoming regenerative. (Author)