The role of the analog designer—and, to some extent, the power-supply designer—has been evolving over the past decade or so. Recently, the trend has been accelerating, driven by ever higher semiconductor integration levels and global changes in product manufacturing.
Integration has been moving upstream from the processor toward a variety of analog peripherals, and manufacturing has been moving to China. The longer version of the story, though, is interesting and instructive.
New Roles
Consider the evolving role of analog designers. At one time, these engineers were expected to be masters of the arcane art of interconnecting an assortment of more or less single-function components. Long ago, they worked with passives and tubes, then transistors, then operational amplifiers and comparators, then simple timing ICs, phase-locked loops (PLLs), analog-to-digital converters (ADCs), digital-to-analog converters (DACs), and so forth.
These designers were engaged with driving analog radios and TVs, oscilloscopes and X-ray machines, and radar sets and bombsights, most of which interacted with the real world in terms of analog signals. More recently, the output became digital to facilitate interaction with microcontrollers or DSPs, which were the domain of the digital designers (see “An Early Experience With Mixed-Signal Design Disciplines”).
Today, it’s different. When mixed-signal chipmakers announce new products, many of these devices, perhaps most of them, are application-specific. They also comprise the entire signal chain, from the sensor inputs that collect analog data in one form or another and turn it into voltage levels through signal conditioning to digitization.
Often, the output is preconfigured for input to one of the chipmaker’s microcontrollers or DSPs. In fact, a complete reference design is usually available. All that is left for the end-product manufacturer to do is to decide which features to implement at which price points and to create a package design that will wrap around the electronics.
Forces for Change
This chipmaker business model seems to be common around the world. The only difference is that in Europe, Japan, and Korea, where IC makers may be part of a larger, vertically integrated organization, the prime customers for new chips may be internal, while for North American chip companies, the customers tend to be manufacturers in China.
For analog design engineers, this change in product integration has altered the career landscape. Except for engineers involved in industrial control and, to some extent, in mil-aero and telecom companies, the jobs that once involved bench design have evaporated.
All of the companies that I have spoken with agree that analog design opportunities have migrated inside the chip companies, where analog engineers may be mixed-signal chip designers or application engineers, either inside or in the field.
The story of how this state of affairs came to pass takes some telling. Obviously, the relentless shrinking of IC design rules, generation by generation, enabled greater integration. But that same relentless shrinking created enormous headaches as operating and allowable input voltages shrink along with feature size.
Refining analog chip design in the analog domain alone probably stopped around the 0.35-µm generation. Ever since then, it has been necessary to accommodate what are essentially noise problems with tricks in the digital domain.
In fact, that design-rule shrinkage has been one of the drivers toward mixed-signal integration. Interfacing a signal-conditioning amp to an ADC no longer can be left to customer engineers, who aren’t intimately familiar with the quirks of the process technology and the often proprietary techniques that have been implemented at all stages of the signal chain.
Chipmakers that don’t want customers complaining that their products can’t achieve their datasheet characteristics in real-world designs must hide their interfaces inside the chip package. Even then, it’s unlikely that the performance of the final product is going to be improved by a customer’s tinkering with the layout developed at the factory.
Hence, we find reference designs complete down to Gerber plots and armies of field application engineers to explain to customers why they really don’t want to save half a cent per board by using cheaper capacitors.