(in Russian, kaskad usileniia), a radio-engineering device that contains an amplifier, a load circuit, and a coupling circuit to the preceding or following amplifier stage. The amplifier may be either an electronic semiconductor device, such as a transistor or tunnel diode, or an electron vacuum tube (receiving amplifier tube, klystron, or traveling-wave tube). A signal fed to the input of an amplifier stage is reproduced with amplification at the output (in the load circuit). The ratio of the output voltage, current strength, or power to the input voltage is called the voltage, current, or power gain of the stage.
According to the frequency or spectrum width of the signals amplifier stages are classified as DC, audio-frequency, intermedi-ate-frequency, or broad-band types; according to the type ofconnection of the amplifier they are classified as common-base, common-emitter, or common-collector stages for a transistorand as common-grid, common-cathode, and common-platestages for a receiving amplifier tube. Amplifiers usually have several stages, which are connected in series. This is called acascade connection—hence, the Russian name for the individual sections.
V. M. RODIONOV