Robert J. Widlar

New developments in IC voltage regulators

A temperature-compensated voltage reference that provides numerous advantages over zener diodes is described along with the implementation of thermal overload protection for monolithic circuits. The application of these and other advanced design techniques to IC voltage regulators is covered, and an example of a practical design is given.

Design techniques for monolithic operational amplifiers

The characteristics of recently developed integrated-circuit components are reviewed and some new devices are described. Their impact on the design of monolithic operational amplifiers is also discussed. Emphasis is placed on realizing particularly good dc characteristics-especially low input current. However, techniques for obtaining higher operating speeds are also covered.

Controlling substrate currents in junction-isolated ICs

Substrate currents can cause a variety of difficulties ranging from improper operation to catastrophic failure. The effects of substrate currents are characterized and techniques are developed for avoiding problems. Method of optimizing layout to control substrate currents and their effects are discussed. It is shown that these currents are strongly influenced by the properties of the die-attach interface. Fault conditions that can generate destructive hole and electron current densities in the substrate are described, and IC clamp diodes, often required to control these fault conditions, are analyzed. An example gives an appreciation of what must be considered in the design of a practical IC along with the results that might be expected. >

A monolithic power op amp

The standard junction-isolated power process has been modified by the addition of polycrystalline-film resistors to solve the topological problems encountered in making 90-W, 80-V, 10-A power transistors and connecting them together for a push-pull output. An all n-p-n output stage that holds crossover distortion to 0.01% while driving a 4- Omega load, even with the quiescent current below 20 mA, has been developed. It is stable with all reactive loads and does not have the spurious-oscillation problems observed with the familiar quasicomplementary amplifier. These innovations are described along with the design of a complete power op amp, the LM12. The prevention of failures from substrate currents which occur when the output is driven outside the supply by inductive loads is discussed. >

Controlling secondary breakdown of bipolar power transistors

An active ballasting technique used to fabricate an oxide passivated power transistor with fTof 50MHz and capable of continuously dissipating 250W with collector voltages above 200V will be reported. Saturation voltage at 10A is under 1V.

INVITED: New approaches for the design of monolithic operational amplifiers

A survey of recently-discovered integrated-circuit elements will be made, explaining their impact on the design of monolithic operational amplifiers with good DC characteristics, especially low-input current, and faster operating speeds.