An Integrated 4-GHz Balanced Transistor Amplifier

This paper presents performance data and design information on a broadband 4-GHz balanced transistor amplifier being developed for possible use in microwave radio relay systems. The balanced stripline circuitry and passive components are integrally fabricated on a 1.5-inch-square alumina substrate using thin-film technology. A comprehensive description is presented of the circuit design, mechanical fabrication techniques, and long-term stability tests. Three-stage amplifiers give 15 dB of gain at 4 GHz with a 3-dB bandwidth of 1000 MHz. Input and output VSWR´S were below 1.05 with a noise figure of 7 dB. A mean time to failure of more than 10/sup 6/ hours has been indicated for a complete three-stage device by data obtained on accelerated component aging tests.