CIRCUIT FOR AUTOMATICALLY CONTROLLING THE GAIN-BANDWIDTH PRODUCT OF OPERATIONAL AMPLIFIERS

摘要

A system for automatically controlling the gain bandwidth product of multiple operational amplifiers fabricated on the same chip, in which one of the amplifiers forms a reference amplifier, and its gain bandwidth product is determined to provide a reference signal used to control a bias circuit determinative of the gain bandwidth products of all the amplifiers, the value of these products being determined by the frequency of a square wave control signal applied to an input of the reference amplifier. The reference amplifier is highly compensated and placed in the configuration of voltage follower so as to generate an alternating exponential ramp signal, which is rectified to provide a series of ramps of common polarity and applied to a voltage to current converter to provide a current signal dependent on the frequency of the control signal and the gain bandwidth product of the reference amplifier. The difference between this current and a reference current provides the reference signal.