Current-Feedback Amplifiers

　　In their effort to approximate the ideal op amp， manufacturers must not only maximize the open-loop gain and minimize input-referred errors such as offset voltage， bias current， and noise， but must also ensure adequate band-width and settling-time characteristics. Amplifier dynamics are particularly important in applications like high-speed DAC buffers， subranging ADCs， S/H circuits， ATE pin drivers， and video and IF drivers （Reference 1） Being basically voltage-processing devices， op amps are subject to the speed limitations inherent to voltage-mode operation， stemming primarily from the stray capacitances of nodes and the cutoff frequencies of transistors. Particularly severe is the effect of the stray capacitances between the input and output nodes of high-gain inverting stages because of the Miller effect which multiplies the stray capacitance by the voltage gain of the stage.