| 摘要 |
A vertical amplifier system for a multitrace oscilloscope including a first and a second variable gain amplifiers each connected to each channel of a multitrace oscilloscope. First, a first reference voltage is fed to the two variable gain amplifiers at the same time. The polarity of output of the second variable gain amplifier is inverted, and the inverted output is added to the output of the first variable gain amplifier by an adder. The added result is detected by a resistor. A CPU automatically controls a gain of at least one of the variable gain amplifiers while receiving the added result so that the added result becomes zero. Second, a second reference voltage (a ground level voltage, for example) is applied to both variable gain amplifiers, and an offset of at least one of the variable gain amplifiers is adjusted so that the added result detected by the resistor becomes zero. The input-output characteristics of both variable gain amplifiers are equalized with high accuracy.
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