| 摘要 |
PURPOSE: A fully differential folded cascode CMOS OP amplifier having an adaptive bias circuit and a common mode feedback circuit are provided to form a high-speed OP amplifier by using a digital CMOS process. CONSTITUTION: A common mode detector provides an output voltage signal proportional to a common mode voltage which is extracted by a common mode reference signal in response to the first input signal, the second input signal, and a common mode reference voltage. The common mode detector includes a plurality of nMOS input terminal differential amplifiers(82,84), a plurality of pMOS input terminal differential amplifier(86,88), and a push-pull CMOS amplifier. The nMOS input terminal differential amplifiers and the pMOS input terminal differential amplifier are used for providing the first and the second current outputs proportional to the common mode voltage. The push-pull CMOS amplifier is used for converting the first and the second current outputs to output voltage signals.
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