| 摘要 |
PURPOSE: An op amp(operational amplifier) with a high gain and a low voltage is provided to improve an open circulation gain of the op amp without addition of another bias circuit by making a gain not change according to a resistive load and by making an output swing(output dynamic range) possibly large in a low voltage operation. CONSTITUTION: An op amp circuit includes a first and second PMOS transistors(MP29,MP30) and a third and fourth NMOS transistor(MN19,MN20). The first and second PMOS transistors connect a gate voltage with an input terminal of an op amp in order to consist of a cas code connection. The third and fourth NMOS transistors serially connect with the first and second PMOS transistors, respectively, and are self-biased into a common gate generating a high gain by complementary self-biasing the first and second PMOS transistors.
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