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In electronics, a comparator is a device that compares two voltages or currents and outputs a digital signal indicating which is larger. It has two analog input terminals and and one binary digital output . The output is ideally : A comparator consists of a specialized high-gain differential amplifier. They are commonly used in devices that measure and digitize analog signals, such as analog-to-digital converters (ADCs), as well as relaxation oscillators. == Differential voltage == The differential voltages must stay within the limits specified by the manufacturer. Early integrated comparators, like the LM111 family, and certain high-speed comparators like the LM119 family, require differential voltage ranges substantially lower than the power supply voltages (±15 V vs. 36 V).〔''(LM111/LM211/LM311 datasheet ). Texas Instruments. August 2003. Retrieved 2014-07-02.〕 ''Rail-to-rail'' comparators allow any differential voltages within the power supply range. When powered from a bipolar (dual rail) supply, : or, when powered from a unipolar TTL/CMOS power supply: : Specific rail-to-rail comparators with p-n-p input transistors, like the LM139 family, allow input potential to drop 0.3 volts ''below'' the negative supply rail, but do not allow it to rise above the positive rail.〔''(LM139/LM239/LM339/LM2901/LM3302 datasheet ). Texas Instruments. August 2012. Retrieved 2014-07-02.〕 Specific ultra-fast comparators, like the LMH7322, allow input signal to swing below the negative rail ''and'' above the positive rail, although by a narrow margin of only 0.2 V.〔''(LMH7322 datasheet ). Texas Instruments. March 2013. Retrieved 2014-07-02.〕 Differential input voltage (the voltage between two inputs) of a modern rail-to-rail comparator is usually limited only by the full swing of power supply. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「comparator」の詳細全文を読む スポンサード リンク
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