Research And Design Of Wideband Power Amplifier

Power amplifier amplifies small signals to specified large ones for loads driving, and transfers them into space with a frequency-modulated antenna. However, with its fast speed of development of Internet of things, transmitters which have multi-channels and transfer quickly in frequency are extremely in need. A complicated resonant power amplifier does not meet the requirements of modern communication. Thus,research and design of wideband power amplifier has significant meanings in modern communication circuit.The technology of amplify with broadband is widely used in radio frequency, whose band covers the whole range of transmitter's operating frequency band. When a transmitter changes its operating frequency, it reaches the output power without tuning. With high frequency transmission-line transformer for impedance matching, a single tube wideband amplifier working in 0.96-1.2 GHz is designed, which has a 46 dBm output and a 33 dB gain. Using circuit design tools like ADS, I design quiescent operating point, amplify circuits, input and output matching circuits, and finally accomplish the whole circuit with simulations and tests.Directional coupler is often used in radio frequency circuit. For its working principle, a four-port coupler working is designed to help detect load and transfer signals to certain circuits. This coupler proves to be successfully designed after several simulations.According to disadvantages in single tube amplifier, new matching networks are designed to provide better conditions for high-power RF signals. Then a push-pull wideband amplifier in same frequency is designed, which has a 51 dBm output and a 68% PAE. After PCB designs and tests, this push-pull wideband amplifier proves to be successfully designed. Finally, a wideband Doherty amplifier based on Class-AB and Class-C is designed, which has a 38dBm output and a 62% PAE.