| 摘要 |
PURPOSE: A differential amplifier having an input range of a rail-to-rail operation from a minimal value of a supply voltage and a maximal value thereof and a constant transconductance is provided. CONSTITUTION: A first differential amplifying section(10) generates a difference between first and second output currents in proportional to a difference between first and second input voltages. A second differential amplifying section(20) generates a difference between third and fourth output currents in proportional to a difference between first and second input voltages. A first level shifter(30) maintains a constant offset voltage difference between the first input voltages of the first and second differential amplifying sections(10,20). A second level shifter(40) maintains a constant offset voltage difference between the second input voltages of the first and second differential amplifying sections(10,20). A current switch(50) divides a common mode input range which the first and second differential amplifying sections(10,20) operate. A first constant current source(60) uniformly maintains the first and second output currents of the first differential amplifying section(10) and the third and fourth output currents of the second differential amplifying section(20).
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