Patent ID: 7420414
Filing Date: 2008-09-02
Classification: H03F

Abstract:
1. An amplifier comprising: an input stage amplifying circuit having a positive phase input node, an opposite phase input node, a positive phase output node and an opposite phase output node, and differential-amplifying a first input voltage inputted to the positive phase input node and a second input voltage inputted to the opposite phase input node, and outputting an input stage output voltage from the positive phase output node; an output stage amplifying circuit amplifying the input stage output voltage and outputting an output stage output voltage from an output stage output node, and generating the second input voltage which corresponds to the output stage output voltage, and feedback-inputting the second input voltage to the opposite phase input node; and a negative feedback circuit having a current source whose output current fluctuates due to the input stage output voltage, and a differential amplifying section to which the output current of the current source is supplied and which differential-amplifies the first input voltage and the second input voltage, the negative feedback circuit feeding-back, to the opposite phase output node, a positive phase current which corresponds to output current of the differential amplifying section.