| 摘要 |
PURPOSE:To improve the characteristic of a differential amplifier by a method wherein gate length of a Schottky gate field effect transistor to be used as the constant current source of the differential amplifier is made to the specified value. CONSTITUTION:When gate length of a Schottky gate field effect transistor using GaAs becomes shorter than 2mum, the voltage current characteristic of the drain thereof becomes hard gradually to be saturated, and when gate length becomes shorter than 1mum, the tendency thereof becomes remarkably abruptly. Accordingly, by using a transistor of gate length of 2mum or more for the transistor Q3 in the figure, a favorable saturation characteristic, namely a characteristic near an ideal constant current characteristic can be obtained, and the characteristic of a differential amplifier is improved remarkably. Moreover, when gate length of the transistor Q3 becomes to 10mum or more, it becomes necessarily to enlarge remarkably gate width to obtain necessary current value, and because it is of no practical use, to make to 10mum or less is necessary.
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