Analog Hotspot

keep hearing people say that the cost of energy is forcing them to choose between paying for gas to get to work, or buying food, or heating the house, or paying the mortgage... So they scrimp as much as they can and then lose their house to foreclosure. That’s very unfortunate. I can’t tell you how to save money on groceries, but other people will tell you how to do that. I can’t tell you all the ways to burn less gas in your car, but it is possible...

An emerging business philosophy in semiconductor design says that the way to prosper in the new global marketplace is to use your engineering skills to design your customers’ products for them—or at least the “hard parts.” One corollary of this is that you have to keep beating your own previous personal-best benchmarks over and over again at the same old 18-month cycles, not just at some component level, but at the subsystem level. The reward is that...

For many years, aficionados of digital circuits and computers have bragged that their rapid advances will leave all analog circuits lying in the dust. The analog business is shrinking, at least compared to the success of digital computers. Moore’s law has made sure of that for many years. The tiny transistors are smaller and faster than ever, even if they can’t stand off 5 V (Fig. 1). ...

Surveying the “high-performance” analog landscape is a lot like looking through a kaleidoscope. With each turn, you’ll see performance characteristics: precision, bandwidth, conversion rates, noise, power consumption, physical size, dynamic range, price, etc. Depending on the application, you may be happy to sacrifice some to optimize others. Turn the kaleidoscope a little, and you’ll see basic topologies or input/output configurations. Turn...

HI BOB, Thanks for the articles on output impedance. They reminded me of the time back in the early 1970s when I was working as a part-time engineering technician (while going to school) for a company that made professional audio tape recorders. I had been working part-time in production test until one fateful day when there was some sort of upheaval in the engineering department. The VP of engineering and senior engineer both quit. The junior engineer was...

Back in the 1960s, I worked with Joe, a good technician who was very analytical. He told me he had put in many months of study to figure out how to bet on horse races. He analyzed all the handicaps, the horses’ records and times, the jockeys’ records, and so on, just as bettors have done for years. After all those months, though, he decided he couldn’t compute how he should bet on horses. His system was never really good enough to actually predict which horse would win and...

The source that drives high-resolution analog-to-digital converters (ADCs) sees a high-frequency ac load and a dc load of a few hundred ohms or more. Thus, a high-performance op amp with high input impedance of a few megohms and low output impedance would be an ideal choice as an input ADC driver. The ADC driver acts as a buffer and a low-pass filter to reduce overall system noise. As signals travel through the traces of a printed-circuit board (PCB) and long cables, system noise...

In my previous column, I took a historical approach to delta-sigma modulation with the single-slope converter (May 8, p. 18, ED Online 18747). Jim Williams of Linear Tech responded, and he sent me a copy of a 1949 article by D.H. Wilkinson on single-slope analogto- digital converters (ADCs). “I’m aware of their obvious weaknesses, but the simplistic elegance of the...

When I present seminars, I often ask the members of the audience to hold up their hands if they think bipolar op amps have better gain and linearity than CMOS. I get a good majority of hands. But neither is bad! The good-old LM301A (well over 30 years old) has a good gain of 260,000 at no load, with just 75 µV p-p of gain error while its output is swinging 20 V p-p (Fig. 1). What happens ...

According to Maxim Integrated Products, the MAX2065 fully programmable, multistate, analog and digital IF/RF variable-gain amplifier (VGA) aims to solve a number of automatic gain control (AGC) design problems in GSM/EDGE, CDMA, WCDMA, LTE, and WiMAX receiver applications (see the figure). But what does that mean? In explaining the thinking that went into the design of the...

Tuners for set-top boxes, DVRs, PC TVtuner cards, and the like keep getting simpler to design in and less demanding to assemble into end products. Anadigics’ AIT1032 1-GHz double-conversion tuner implements upconverter, downconverter, voltage-controlled oscillator (VCO), synthesizer, RF and IF amplifier, and RF and IF gain control functions with a combination of gallium-arsenide (GaAs) and silicon technologies. It’s designed to avoid...

Download the full article as a .PDF, sponsored by Analog What are digital potentiometers, and how are they used? Digital potentiometers are integrated circuits that implement a resistive ladder and a digital means of addressing a particular tap on the ladder that corresponds to the wiper position of a mechanical potentiometer. They’re used to...

HI BOB, I have been collecting some new but mostly museum-grade test instruments. Along with purchases from various instrument rental houses, flea markets, and so on, for a while I bid on items in government liquidation auctions. Occasionally, I won. The starting bid was always $50, and some I got at that price. Some went way higher but seldom approached the original list price, and I gave up way before that. Often, the shipping costs to a pickup and forward...

It’s possible to build a push-pull amplifier using amplifier ICs, rather than discretes, as in the traditional class B amp (see the figure). A bridged-amplifier configuration effectively doubles the voltage swing at the load. It’s also possible to build a bridge amplifier in which one stage drives one side of the speaker and a second unity-gain inverting amplifier drives the other side of the speaker. However, the...

Amplifiers are fundamental circuit-design elements. They drive everything from earbuds to antennas. Placed ahead of analog-to-digital converters (ADCs), they reshape signals from sources as diverse as strain-gauges to ultrasound probes. Through proper selection of feedback passives, they can be configured into high-pass, low-pass, band-pass, and band-elimination filters. Feed them with multiple signals, and they produce harmonic series of all the...

The mainstream media may call it a digital age. But today’s gadgets still need integrated circuits that can transform analog signals—which convey information about “real world” phenomena like temperature, pressure, sound, and speed—into digital form. Linear Technologies is one of the leading companies designing, manufacturing, and marketing a broad line of standard high-performance analog integrated circuits as well as devices that control power and regulate voltage in...

Download the full article as a .PDF, sponsored by Analog What are VGAs? Variable gain amplifiers (VGAs) are signal-conditioning amplifiers with electronically settable voltage gain. There are analog VGAs and digital VGAs, or DVGAs. An analog voltage controls the gain in both, which differ in how it is applied. A digital-to-analog converter ...

HI BOB, Any big trips to exotic spots planed this year? We’re headed for Newfoundland and Prince Edward Island for a change of pace. (I may go to Scotland in September. /rap) My question: Do you have some circuitry I could use for an electronic bagpipe simulator? It would need nine notes selected by removing fingers from some form of contact that would reasonably simulate a finger hole. I don’t need too many...

Suppose you were designing a digital camera, and you wanted to extend its battery life by turning off its big power-hungry display screen whenever its users have their eye up to the optical viewfinder. Or suppose you were designing a notebook and you wanted a feature that would turn the keyboard backlight on only when the user’s hands were near the keyboard. Or suppose you were designing a touchscreen phone and you wanted to deactivate the on-screen buttons when...

One day, back about 1966, I was going up the elevator at 285 Columbus Avenue in Boston to look at some production problems on Philbrick’s fifth floor. And who was in the elevator, but George Philbrick’s friend Jim Pastoriza. Jim was going up to show George his new analog computer demonstrator—portable and battery-powered. In fact, it was running, and he gave me a demo right on the elevator as we ascended. And, this modular analog computer ran on a couple of...