A transistor operational d.c. amplifier
W. Hochwald, F. H. Gerhard · 1956
The d.c. operational amplifier is the most important in the line of component building blocks used in an analog computer. Equipped with appropriate input and feedback networks, this amplifier is capable of voltage or current summation, integration and differentiation. Present day applications in airborne computer systems frequently demand accuracies of 0.01% or less while necessitating the utmost in ruggedization, reliability, and minimization of volume, weight and power consumption. To meet the accuracy requirements, drift stabilization by means of a low-drift carrier-type preamplifier is normally required. The amplifier discussed here employs this principle in a manner similar to that developed by the RCA Research Laboratories (Project Typhoon, 1947). To meet the requirements of airborne use, transistors may be ideally employed. While it is now possible to achieve the requirements using semiconductors throughout the amplifier, this paper covers an interim version which employs transistors in all but two critical portions of the circuitry.