Thomas M. Frederiksen

A new current-differencing single-supply operational amplifier

The conventional integrated-circuit operational amplifier is not well suited to many system applications that operate from only a single power supply voltage. To more optimally meet the requirements of industrial control systems a new current- differencing opamp has been developed that uses a simple circuit to provide a gain element that out performs the 741 IC opamp. As a result of the circuit simplicity, multiple opamps are possible and six independent internally compensated amplifiers have been fabricated on a single 80/spl times/93-mil die. Many circuits are presented only not to show how this circuit can perform most the application functions of a standard IC opamp, but also to indicate the increased usefulness of this new input current differencing type of opamp circuit in single power-supply control system applications.

A monolithic high-power series voltage regulator

A complete series voltage regulator circuit capable of delivering /SUP 1///SUB 2/ ampere of current has been built on a single 63/spl times/66-mil die using the conventional all- diffused processing technology. Improved performance has been achieved by using an internal low-power voltage regulator to supply the desired dc output voltage reference directly to a second main regulator. This permits the dc and ac characteristics of the regulator to be separately optimized with the result that excellent transient characteristics are realized simultaneously with low drift and excellent regulation.

A High-Performance 3-Watt Monolithic Class-B Power Amplifier

A monolithic class-B power amplifier has been built that is capable of delivering 3 watts sinewave power to a direct-coupled load with less than 0.4 percent total harmonic distortion over the range from 20 Hz to 20 kHz. It occupies a single 45 by 60 mil die and is fabricated using conventionrd all-diffused processing technology. The circuit employs an all n-p-n, direct-coupled, transformerless output stage which is well suited for fabrication in integrated form. Excellent biasing characteristics are achieved by introducing a deadband at the output of the amplifier and using overall feedback to linearize the response. Analyses are made of the amplifier linearity, dc drift, stability, and large signal behavior. Simple design equations are derived which accurately relate the important circuit variables to amplifier performance.

Multiple, high-gain, common-emitter operational amplifiers using super-ß lateral transistors

Six independent, internally-compensated high-performance op-amps have been built on a single monolithic chip. They were designed for industrial control and automotive electronic systems which require low-cost single-supply amplifiers.