| 摘要 |
PURPOSE:To realize an operational amplifier where the range of a common mode input voltage has a wide range from a negative power voltage to a positive power voltage by connecting the 2nd differential pair to an input differential pair via a source follower. CONSTITUTION:An input signal is fed to the 1st differential pairs M1, M2 from an input terminal 1 and fed to the 2nd differential pairs M21, M22 via source followers MS1, MS2. When the common input voltage is equal to a load power voltage, since an input signal subjected to level shift by the source followers MS1, MS2 is fed to the 2nd differential pairs M21, M22 even when the 1st differential pairs M1, M2 are turned off, the function as the operational amplifier circuit is not stopped. When the common mode input voltage rises up to the positive power voltage and the source followers MS1, MS2 are turned off, the current in the 2nd differential pair is decreased and a current flows also to the 1st differential pair, the stable operational amplification is attained in this case.
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