Systemizing the Design of Broadband Class-A RF Power Amplifiers

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  • Author: Firas Mohammed Ali (The Higher Institute of Yefren)
In the design of broad-band microwave amp-lifiers, there are two techniques that are typi-cally used to achieve gain-flatness across the frequency band of inter-est. The first technique is done through selective mismatch at lower fre-quencies of the band where the power gain is significantly higher. This can be achieved by degrading the VSWR at input or output at the low frequency band edge. The second tech-nique is implemented by adding dissipative compensating networks. The input matching network is first designed to achieve minimum VSWR over the full band, and the required gain leveling is then done by adding the lossy equalizing circuit. This network is a constant resistance network and must have a roll-up insertion loss characteristic to compensate the inherent roll-off gain characteristic of the RF transistor over the entire frequency band.