The power stage of servovalves is spool valve, playing the role of hydraulic pressure amplifier.

电液伺服阀的功率级一般为滑阀，起液压放大器的作用。

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Purpose: Power amplifier applications, driver stage amplifier applications.

用途：用于功率放大、驱动级放大。

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There are three development for the Middle Power Amplifier : the first stage power amplifier, the drive stage power amplifier and the last stage power amplifier .

本文对固态线性功率放大器的研制包括：前级放大器的研制、驱动级放大器的研制、末级放大器的研制。

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