Op amps have been further refined into other specialized devices. Along with these, a wide range of specialized linear integrated circuits have emerged. In the area of simple amplifiers, devices are available that are designed to work primarily from single polarity power supplies. Also, a large array of specialty amplifiers exist for such applications as low noise audio pre-amplifiers. For very low offset applications, specialized “auto zero” amplifiers are available. These amplifiers continually monitor their DC offset and actively correct it.
Moving away from the strict confines of op amps, linear ICs are available for most popular functions, making the designer's job even easier. Some of these items will be explored in later chapters. Other devices are for very specific applications and will not be covered here.
Some manufacturers develop ICs solely for specific market segments. As an example, Analog Devices, THAT Corporation and Maxim make very specialized ICs for audio and musical equipment manufacturers. The Analog Devices SSM line includes high precision microphone pre-amps and low power loudspeaker and headphone amplifiers. In like fashion, THAT Corporation makes voltage-controlled amplifiers, balanced line drivers, dynamics processors and other items aimed at the audio industry. Maxim makes a series of audio subsystem ICs for notebook PCs and mobile communications. Of course, nothing prevents a designer from using one of these ICs in a non-musical product.