Amplifiers are the hidden heroes of any system, and often unappreciated even as their role changes and expands.
Amplifiers are the hidden heroes of any system.
We often take for granted that amplifiers can handle any input signal voltage ranging from microvolts to beyond the power supplies, operate on almost any voltage, and output a signal that can drive the following stage.
At the same time, the amplifier must protect the system from anything that could be connected to the input purposely or accidentally. They might not be as sexy as the latest MEMS gyro or A/D converter, but amplifiers perform real and necessary functions in most electronic systems. Because of this near ubiquity, they are particularly good bellwethers of industry trends.
Two key trends that have been steadily growing for years, and are poised to gain significant momentum in 2012, are the migration towards zero-drift capability and the much-greater range of voltages that will be seen at the supplies and the inputs.
Operational amplifiers, among the most widely used components, can be found in virtually all types of systems. They are an essential building block for functions such as filters and instrumentation amplifiers. Each function requires specialized performance, causing the evolution of many performance parameters or features to suit various applications. Op amps may be selected for speed, noise (voltage, current, or both), input offset voltage and drift, bias current, and common-mode range. Other factors include power output, ambient temperature range, supply voltage, and packaging.
The continued migration of configurations and functionality, from single amplifiers into functional blocks, has created many different categories of amplifiers, enabling higher performance and simplifying the design process. Even more than before, op amps are becoming the “proving ground” for many of the features and functions that are later designed into specialty amps.
These high-performance devices, which include instrumentation amps, current-sense amps, differential amps, and programmable-gain amps, are designed for specific signal types, and extract and amplify the signal of interest. These different classes of amps perform a variety of functions, including capturing and filtering low-level ac signals, providing automatic gain and converting picoamps of current to precision voltage signals.
Zero-drift amplifiers exemplify this trend. A technique originally developed to address constantly changing temperature as well as drift over time, today’s zero-drift amplifiers dynamically correct offset voltage and reshape noise density as well. Zero-drift amplifiers were originally used in systems with an expected design life of greater than 10 years, and in signal chains that use high closed-loop gains (>100) with low-frequency (<100 Hz), low-amplitude signals. Examples can be found in precision weigh scales, medical instrumentation, precision metrology equipment, and infrared, bridge, and thermopile sensor interfaces.
In addition, zero-drift amplifiers have nearly zero offset, and higher open-loop gain, power-supply rejection, and common-mode rejection as compared to standard amplifiers. In the future, we’ll see more complex instrumentation- and difference amps that take advantage of zero-drift functionality to provide designers more design options for their applications.
Wider range of supply and input voltages is a trend that challenges op amps more than any other system component. High supply-voltage amps are powered by systems that connect to power systems, automobiles, or large battery packs. In these systems, the amplifier’s input may be connected to hundreds of volts and must still amplify signals in the microvolt range. These amps have evolved over the years to include features such as integrated input OVP (over-voltage protection), on-chip EMI (electromagnetic interference) filtering, higher ESD (electrostatic discharge) immunity, and greater resistance to latch-up in both powered and unpowered operations.
Increasingly, high-voltage amplifiers also offer features to improve system performance, cost, and robustness, while easing the complexity of system design in applications ranging from portable telecommunications equipment, power-supply control and protection, and interfaces for transducers with wide output ranges. In the coming years, additional current-sense, instrumentation, and other specialty amps with wide supply-voltage capability will be introduced into the market, offering designers a significant step forward in functionality.
Amplifiers really are the hidden heroes of most electronic systems, and the highly versatile op amp not only fills an extremely important role within the electronics industry, but its evolution is spawning new ways of signal conditioning that can be applied more broadly across many classes of amplifiers that in turn are used in many different applications. Two key capabilities we see spreading even more broadly over the market in the coming year are the inclusion of zero-drift and wide supply-voltage features in a growing range of specialty amplifiers.
About the author
Steve Sockolov is director of Linear and RF Core Marketing,, Analog Devices, Inc. (San Jose, CA). He is responsible for the product and business development strategy for the linear and RF groups. Steve can be reached at firstname.lastname@example.org.
(Also see a companion piece, "Smarter Converters — the 2012 trends in data conversion", click here.)