A Coupling Matrix Synthesized Three-Dimensional Filtering Power Amplifier

This paper introduces a coupling matrix synthesized filtering power amplifier (PA). In conventional filtering PAs, impedance matching is usually implemented through lumped or distributed circuits based approaches, such as the even-odd mode analysis or the equivalent circuit transformation. However, they are difficult to be applied in three-dimensional (3D) circuits, where exist electric/magnetic resonances and mutual couplings. Herein, a general $N+3$ coupling matrix is synthesized, which the 3D physical structure can be determined directly, regardless of specific lumped/distributed circuit values. The $N+3$ matrix enables explicit efficiency calculation of the amplifiers as well as scattering parameters, which offers a comprehensive evaluation and prediction of the circuits' performances. Moreover, the coupling matrix facilitates easy integration of the on-chip transistor with the 3D high-Q resonators. Thus, conventional planar matching circuits can be removed, allowing for reduced losses and compact architecture. The technique will be more valuable for millimeter or terahertz waves as the operating frequencies, and therefore, planar circuit losses increase.