Design Methods of Outphasing Transmitter Exciter for Lab Prototyping

The paper presents a prototype digital signal component separator (SCS), for a power amplifier, built using the outphasing technique. An analysis of the shortcomings of the previously developed analog-digital SCS is provided, which led to the selection of a fully digital implementation based on a personal computer and a multichannel sound card. Algorithms for generating amplitude-phase, amplitude, and frequency modulated signals are developed using a digital signal processor (DSP), which offers high flexibility in configuration and precise signal synthesis. The structure of both software and hardware components of the SCS is described, including the implementation of a Hilbert transformer, quadrature modulators, and the interface for communication with analog blocks. Experimental studies confirm a low level of nonlinear distortions (down to $\boldsymbol{-} \mathbf{7 0} \mathbf{~ d B}$) and showed the practical applicability of the proposed solution in the development of outphasing transmitters. The results demonstrate the potential of digital outphased signals generation techniques to enhance the efficiency and stability of outphasing radio transmitters.