Low-noise amplifiers in wireless communications: state of the art, two new wideband all-active LNAs in SiGe-BiCMOS

The aim of this paper is three-fold. First, it introduces the low-noise amplifier, its relevance in modern wireless communications receivers and the performance expected of it. Then, it presents an exhaustive review of the existing topologies, presenting their advantages and shortcomings. And finally, it introduces a new class of LNAs, based on current conveyors, describing the founding principle and the performances of two new LNAs, one single-ended and the other differential. Both these new LNAs offer the following notable advantages over existent topologies: total absence of passive elements (and the smallest LNAs in their respective classes); wideband performance, with stable frequency responses from 0 to 3 GHz; easy gain control over wide ranges (0---20 dB). Comparisons with other topologies prove that the new class of LNA implementations greatly advances the state of the art. These amplifiers are ideally suited to today's multi-band receivers.