The Variable-Capacitance, Parametric Amplifier (Übersicht über parametrische Verstärker mit gesteuerten Kapazitäten)

Zusammenfassung

For many years vacuum tubes have been the only means for obtaining low-noise amplification at microwave frequencies. Not only have these well-established tube amplifiers been improving continuously, but in some instances they have even surpassed performance goals set by accepted theory. This monopoly of the vacuum tube has not been seriously challenged by the transistor even though great strides have been made in extending its operation to higher and higher frequencies. Within the last two or three years, however, we have witnessed solid state art enter the field of microwave low-noise amplification and become firmly established in it. There have been three solid-state entries, namely, the maser, the variable-capacitance amplifier and the variable-inductance (or ferromagnetic) amplifier. The first two, i. e., the maser and the variable capacitance amplifier, have already yielded experimental results which point to early and important system applications.