Patent ID: 7414474
Filing Date: 2008-08-19
Classification: H03F

Abstract:
1. An operational amplifier which amplifies a difference between two input voltage signals to a non-inverting input terminal and an inverting input terminal and then outputs the amplified difference to an output terminal, the operational amplifier comprising: an input voltage/current conversion stage which outputs, to the non-inverting input terminal and the inverting input terminal, a current signal reflecting a difference current component in accordance with the difference between the two input voltage signals; a current amplification stage which outputs a current signal obtained by performing current amplification on the current signal outputted from the input voltage/current conversion stage; and an output buffer stage which converts, into a voltage signal, the output current signal from the current amplification stage and applies the voltage signal to the output terminal; and wherein the input voltage/current conversion stage outputs a complementary pair of current signals having a difference current component, and wherein the current amplification stage adds and synthesizes a pair of electrical signals outputted from the input voltage/current conversion stage, and outputs a current signal obtained by performing the current amplification only on the difference current component.