A Simple Microwave Power Combining Amplifier with Enhanced Linearity and High Out-of-Band Rejection

We present the design and implementation of a power combining amplifier that has a bandpass response, providing high rejection to spurious frequencies and intermodulation products that are usually generated in transmission systems. The proposed architecture consists of two identical power amplifiers interconnected with compact microstrip filtering power dividers and combiners. A prototype capable of operating at 2.3 GHz was fabricated to validate the design. The obtained measurement results demonstrate that high out-of-band rejection is achieved, while the 1 dB compression point is enhanced about 1.6 dB with respect to the individual amplifiers. In addition, thanks to the low insertion loss of the combining components, the total gain of the system is not considerably reduced.