Discrete Op - Amp THE JOHN HARDY COMPANY

The 990 discrete op-amp is the finest op-amp available for audio applications. If you want superior sound quality, the 990 can provide it. The 990 is used in the most critical audio applications. Leading recording studios, remote recording companies, disc and CD mastering facilities, TV and radio stations use the 990 for superior performance. Several mic preamps and other products using the 990 are available from the John Hardy Co. Features Circuit design of the 990 is by Deane Jensen of Jensen Transformers, who was awarded U.S. patent #4,287,479 for this design. Every aspect of the 990's design and performance was optimized through extensive computer aided design and analysis. Each component of this discrete op-amp was carefully chosen for its specific task, providing superior performance compared to monolithic op-amps and other discrete op-amps. For complete design theory, circuit details and specifications, please see the Jensen engineering report. Packaging and production design of the 990 is by John Hardy of the John Hardy Co. The design enables this 41-component circuit (44 components for the 990A and 47 components for the 990C) to be constructed on a circuit board 1 " square, with final module dimensions after encap-sulation of 1.125 " square by 0.600 " high. The dimensions and pinouts conform to the API-2520 package, allowing direct replacement in most applications. Discrete vs. monolithic op-amps. An op-amp typically consists of dozens of diverse components including transistors, diodes, resistors, capacitors and occasionally , inductors. The fundamental difference between a discrete op-amp and a monolithic op-amp is the way these diverse components are brought together to make a working op-amp. A discrete op-amp is made from individual (discrete) transistors, diodes, resistors, ca-pacitors, and occasionally, inductors that are brought together on a circuit board or other substrate to create the final circuit. Each diverse component is fabricated on a manufacturing line that is fully optimized for that specific part. Therefore, each component is the very best it can be. Low-noise input transistors are fully optimized for their unique requirements, high-power output transistors are fully optimized for their unique and very different requirements. Precision resistors come from manufacturing lines that are dedicated to making precision resistors. Capacitors come from optimized capacitor lines. Only after these fully optimized components are fabricated are they brought together on a circuit board or substrate. A monolithic op-amp starts with a single chip (monolith) of silicon that is typically 1/16 " …