Differential amplifier and two-step parallel A/D converter

摘要

The present invention is directed to improvement of a differential amplifier an its peripheral components employed in an A/D converter to enhance an accuracy of the A/D converter. The differential amplifier has an amplifying element comprised of a pair of differential transistors Q1 and Q2, emitter resistances 2a and 2b, and collector resistances 2c and 2d. The differential amplifier has transistors Q3 and Q4 constituting an emitter follower for applying an output amplified in the differential amplifying element to the outside. The differential amplifier includes transistors Q5 and Q6 having their respective base electrodes connected to input terminals 4a and 4b and serially connected to the transistors Q3 and Q4, and resistances 2e and 2f interposed between emitter electrodes of the transistors Q5 and Q6 so as to relieve any influence of variations in base-emitter voltages of the transistors Q3 and Q4. Effectively an output from the emitter follower can be improved and a gain of the differential amplifier and linearity can be also improved.