Signal Reconstruction in Digital Transmitter Drives

High-power transmitters usually consist of two major units: transmitter drives (TDs) that perform all "intelligent" functions of the transmitters, and power amplifiers (PAs) that carry out final amplification and antenna coupling. In low-power transmitters, TDs and PAs are usually combined. Virtually all modern TDs are digital. However, they contain fairly large analog and mixed signal portions (AMPs) in addition to their digital portions (DPs). The AMPs limit accuracy of modulation and spreading, adaptivity, reconfigurability, and scale of integration of the TDs. As was previously shown, conventional reconstruction technique is the main cause of these limitations. This paper reveals the logic and main trends of the development of sampling and reconstruction techniques that are closely connected, provides consistent and comprehensive analysis of baseband and bandpass reconstruction, examines various reconstruction techniques, shows potential capabilities of reconstruction circuits (RCs) with internal filtering, and determines theoretical restrictions imposed on weight functions of these RCs.