Dual-Input PA Architectures for High-Efficiency Radar and Telecommunication Transmitters
In this talk, multi-input PA architectures and suitable test platforms are discussed with the aim of improving the limitations of single-input PAs in efficiency and bandwidth. Multiple inputs can be at RF, at Low-Frequency (LF) analog or digital, or a combination of both. Both information-carrying and control signals must be calibrated and time-synchronized at the DUT reference planes. For example, efficiency enhancement in backoff can be provided with out-phasing PA architectures which requires accurate synchronization in amplitude and phase of 2 RF signals. Dual-band amplifiers with two broadly separated bands can be seen as a multi-input PA where a number of signals at different carrier frequencies are concurrently present at the PA input. In Envelope Tracking (ET), a LF signal is used to control the dynamic supply to provide backoff efficiency enhancement of a RF PA. A new concept of dynamic supply for ET is discussed which employs a LF digital control and a LF digital feedback in the setup to allow hardware complexity simplifications. In this talk we discuss the problems and solutions of generating RF (at 1 or multiple carriers) and LF signals at the PA input, in a calibrated and time-synchronized manner. Modular instrumentation is particularly suited to this since it allows to reconfigure the setup mostly by software and by adapting the DUT interfacing (driver and attenuators mostly).