| 摘要 |
An operational amplifier is provided to increase a bandwidth of the operational amplifier by frequency-compensating a first common mode voltage irrespective of a differential input signal. An operational amplifier includes an input amplifier(100), a first common mode feedback amplifier(110), a cascode amplifier(120), a first common mode voltage generator(130), and frequency compensating capacitors(C11,C12). The input amplifier amplifies a differential input signal. The first common mode feedback amplifier amplifies a first common mode voltage. The cascode amplifier cascode-amplifies output signals from the input amplifier and the first common mode feedback amplifier. The first common mode voltage generator generates a middle voltage of the output signals from the cascode amplifier and applies the neutral voltage to the first common mode feedback amplifier. The frequency compensating capacitors feeds back the output signal from the cascode amplifier to the first common mode feedback amplifier and compensates for a frequency of the feedback signal.
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