| dc.description.abstract | This thesis focuses on the design of novel microwave bandpass power amplifier. By integrating the functions of bandpass filter and power amplifier, novel multi-functional RF component is achieved, which can help reduce the circuit size and improve the level of integration of RF transmitter. The proposed method of realization is based on introducing the bandpass filter design flow into the matching network design of power amplifier. Two design examples are present to validate the effectiveness of proposed design method and the circuit performance.
First, at 1.95 GHz class A bandpass power amplifier is implemented, in which the 2nd-order Chebyshev bandpass response is used to design the input and output matching networks. In order to enhance the design flexibility of bandpass matching network, immittance inverters are adopted in the proposed circuit structure. The bandpass power amplifier is implemented on printed circuit board using packaged HEMT and chip components. Due to the bandpass matching networks used, very good harmonic suppression is achieved. The 30 dB upper stopband rejection is up to 5f0. Especially, the second and the third harmonic levels are below −45 dBc and −60 dBc, respectively.
Next, the 1.95 GHz class AB bandpass power amplifier design is implemented using the same technique. The measured results show that 25 dB upper stopband rejection is also up to 5f0. Notably, the second and the third harmonic levels are below −50 dBc and the fourth as well as the fifth harmonic levels are below −70 dBc.
The proposed bandpass power amplifier is composed of the functions of bandpss filter and power amplifier with complete and systematic design procedure. Compared with conventional ones, the propsoed bandpass power amplifier features better selectivity, wider upper stopband, and better harmonic suppression with about the same circuit area.
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