The Other Technology — An Outlook

  1. Even the process innovations were driven by an individual circuit designer or a small group at most, not an obvious industry-wide push by large teams of engineers.

APPLICATIONS

Let me show you how linear circuits are used in conjunction with other devices or end products you’re familiar with.

Personal Computer

The next slide shows a personal computer arrangement. Now even I think of a personal computer as a digital machine, with digital in through the keyboard to the digital computer inside the machine. But a close look reveals lots of linear:

  • Op-amps, comparators, voltage regulators, and other linear circuits in the disk drive
  • More op-amps, comparators, regulators, and driver circuits in the printer
  • and so forth

Disk Drive

If you look at the disk drive part of the personal computer setup you’re talking about another whole industry. The disk drive in the personal computer includes some linear. But when you look at the more sophisticated drives, you’ll find that the accurate positioning of the head on the disk and the recovery of the data from the disk both rely on linear ICs.

Scale

Another system that you’ve all been exposed to is the supermarket scale hooked up to an electronic cash register. In this application, linear ICs must provide data that is 1 part in 2,000 absolute accuracy (0–20 lbs +/– 0.01 lb). Although the cash register’s main function is digital, it relies on linear circuits to amplify the low-level signal from the weighing platform, as well as convert the linear weight data into a digital format suitable for the computer.

CAT Scanner

This slide shows a medical application that is linear IC intensive. In a CAT scanner, the donut-shaped assembly rotates about the patient. As it rotates, the amount of x-ray energy presented to each detector will vary depending upon the density of tissue being examined. The computer in combination with the instrument’s rotational motion executes a complex analysis allowing a three-dimensional representation to appear on the display. Although the instrument uses a computer to generate its output, it relies on linear ICs to accurately convert the x-ray detectors’ output to digital signals. As many as 1,000 detectors may be used and each detector has an amplifier and a high-performance one at that.

THE LINEAR MARKET

The linear portion of the total semiconductor industry is a steadily growing sector. This slide shows the growth enjoyed by U.S. suppliers as tracked by SIA from 1976 to 1981.

TRENDS

The first trend I’d like to describe is in the area of power. The power trend is going in two opposite directions.

MORE SYSTEMS ON A CHIP

More systems on a chip is an important subject these days. Systems often require a combination of digital and linear functions. The linear world has been watching the digital side of the business attempt to integrate what we think are linear elements on-board the microprocessor. Intel’s 8022 and 2920 are good examples. Digital VLSI technology has progressed to the point of doing large digital systems on a single chip. There has been some demand to incorporate analog or linear functions on the same VLSI chip. This has been done with limited success for a couple of reasons. The quality of the linear function available on the digital fab process is low and the expertise required to do the linear function, for the most part, has not been available to the digital company. Notwithstanding these problems, the trend is real and will continue. As the digital IC becomes larger, it’s possible via CAD techniques to incorporate more linear commodity-class functions. The next slide shows our perception of the degree of combination feasible today.

  • The wafer fab process is compatible
  • The testing skills are compatible, and
  • It doesn’t burden the processor with the A/D

MORE MIXED PROCESSES

This next slide shows some basic wafer fab technologies available to the linear IC manufacturer. There are basic bipolar and CMOS processes and a variety of adjunct processes. This adjunct variety is so named because they can be combined with either bipolar or CMOS.

  • If you short-circuit the output, it’s protected
  • If you over-voltage it, it’s still protected
  • If you run it too hot it will shut itself down

Unlisted

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Engineer, sustainability, indigenous history, analog electronics history and anything that supports my belief that bikes can save the world.

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Todd Nelson

Todd Nelson

Engineer, sustainability, indigenous history, analog electronics history and anything that supports my belief that bikes can save the world.