Analog Hotspot

Once upon a time, if you wanted to make a junction transistor, you could start with a small seed crystal of pure germanium. Using Czochralski's 1917 methods, the crystal was gradually rotated and pulled out of a lightly doped N-type material and grown into a small boule. After suitable growth, a small amount of acceptor impurity such as gallium was added to the melt, causing the germanium to form a PN junction. This was all consistent with the theory of William Shockley, published...

A precise, temperature-compensated voltage reference circuit lies at the heart of every analog-to-digital converter. Voltage-reference technology hadn't changed fundamentally in decades until last year, when Intersil announced a single reference chip based on precharging a floating gate. The company now has announced several additional voltage references. But first, let's look at the technologies. "Bandgap" voltage references have been around since Bob Widlar developed...

Hi Bob: I was just reading your column in the Nov. 16, 2006 issue of Electronic Design ("What's All This SiO2 Stuff, Anyhow?" p. 18) and had some insights. The silicon dioxide (SiO2) added to foods for anti-caking is a little bit different from sand. Chemically, it's the same, but it's made by dissolving SiO2 in some really nasty acids and then flashing the acids off. What's left looks like a semi-solid fog. My old boss used to...

Meeting the need for analog-to-digital converter (ADC) sampling at rates beyond 135 Msamples/s in WiMAX applications, Analog Devices' AD9640 is the first dual 14-bit analog-todigital converter (ADC) to offer 150 Msamples/s. It provides two ADCs in the same footprint as previous single ADCs with the same performance. Also, it offers an onchip clock divider and digital inputs to the receiver-system automatic gain control (AGC) circuitry (...

There are lots of ways to shift logic levels. But for versatility in a small footprint, it's hard to beat Fairchild's FXL2TD245 dual-supply bi-directional translator, with its configurability for both uni-directional and independent bi-directional voltage translation between two logic levels. The chip permits translation between levels from 3.6 V down to 1.1 V (...

What is a synchronous rectifier? A synchronous rectifier is a circuit that emulates a diode, allowing current to pass in one direction but not the other without the losses associated with junction or Schottky devices. The circuit comprises a pass-element (most often a power MOSFET), a sense element, a sense-signal conditioner, and a driver. How does a synchronous rectifier work? There are two broad techniques to implement the...

Over the last several years, we've seen ICs wrap lots of applicationspecific functionality around a mixed-signal core, ultimately creating a canned solution for consumer-products OEMs. Expect more of the same this year. For example, there's Wolfson Microelectronics' WM8781 (see "Digital TV, Audio Boost Analog/Mixed-Signal." This high-input-voltage, 24-bit, sigma-delta analog-to-digital converter (ADC)...

Interesting new applications continue to emerge within the world of amplifiers. In some cases, the applications themselves are novel. In others, the combination of applications and their influence on architecture constitutes the story. Sometimes, the application provides unexpected insight into consumer behavior. For reasons of battery life, efficient Class D amplifiers are squeezing their way into cell phones, particularly as mobile phones become repositories for downloaded music...

Last October, Advanced Analogic Technologies acquired a Chinese independent design house (IDH), Analog Power Semiconductor Corporation. Analogic is nowhere near the size of ADI or National Semiconductor, so acquiring the 25-person company literally doubled its engineering headcount. These days, many Asian-born entrepreneurs get a few years of analog experience in the U.S. under their belt before returning home to found startups like AP Semi and train a new generation of analog...

As much as we'd like to think engineering is all about innovation, the essence of the profession often comes down to answering three questions: Who is the customer, what does it want, and how am I going to do it? As a result, interactions between designers and customers tend to define our goals and tasks. OEMs, IDMs, And IDHs, Oh My! Consumer products dominate today's analog/mixed-signal chip market, and most of the customers are Asian...

Watch an LCD TV or surf the Web on your refrigerator. Chat with your washing machine. Let your dishwasher decide when the dishes are done. Enjoy a hot cup of joe with just the right amount of cream and sugar, dispensed by your coffee maker with skill that would put any barista to shame. And you won't need to wait decades for these advances. They're happening right now. There's a revolution in modern white goods as the industry moves from its electromechanical ...

Today's trend toward more functionality in portable products affects everything, including I/O ports. The FSA201 and FSA221 multimedia switches from Fairchild Semiconductor let designers run audio through their product's USB connector when it isn't being used for data. In that case, a cell phone could use either switch to supply audio to a headset or exchange data with a laptop via the same connector (...

The analog world saw a host of significant but incremental developments in 2006. Take data converters. Back in January, the delta-sigma architecture was enjoying a renaissance as it was applied at remarkably high input signal frequencies, thanks to new developments in clock stabilization. For example, at last winter's ISSCC, Xignal disclosed the details of a 640-MHz CMOS continuous-time delta-sigma analog-to-digital converter (ADC) with a 20-MHz signal bandwidth and a 12-bit...

I've been working with precision op amps. Some have good linearity. Some are excellent. Some have high ZOUT. Some have low. Some are bipolar, others are CMOS. The figure shows the basic test I've been using for linearity to exercise the output to 20 V p-p by applying a ±10-V sine or...

The votes are in. Electronic Design's readers selected Akustica's AKU2000 microelectro-mechnical-system (MEMS) microphone on a chip as the most significant Leapfrog technology of the year (see "Breaking A New Sound Barrier: It's A Mic-On-A-Chip," April 27, 2006, p. 36, ED Online 12361). This CMOS device breaks new ground in size, cost, and performance parameters. Akustica hasn't rested on this achievement, though. The first-generation AKU2000 features an acoustic...

There is indeed a shortage of analog designers. But it's less a shortage of circuit wizards like Bob Pease than a dearth of well-seasoned engineers who could create user-friendly mixed-signal designs on a piece of silicon. The underlying need is for increased industry-university outreach to engineering undergrads. In the meantime, the EDA community is hard at work making mixed-signal chip design easier. For example, Cadence Design Systems recently updated its Virtuoso...

The first time I noticed this, I was camping up in the Sierras. Some people will even read the fine print on a ketchup bottle if there's nothing better to read. But we didn't have any ketchup bottles. So I was reading the information on an envelope of some bean soup—beans, dried onion, salt, spices, etc.—and silicon dioxide? Hey, I know what that is, and I wonder who gives them permission to put sand in the dehydrated bean soup. When I got home, I...

Several key issues will determine when digital TV (DTV) will reach ubiquity and succeed in the marketplace. Once in place, it will have some major implications on business and personal life: Multiple standards will exist: We already have multiple standards, and that will continue. Over-the-air TV will use the ATSC standard in the U.S. We’ll continue to have satellite DTV. Cable companies will still have their own brand of...

Let's get one thing straight: Digital TV is not synonymous with high-definition digital TV (HDTV). It's much more than that. Digital TV encompasses not only HD, but satellite TV, cable TV, Internet Protocol TV (IPTV), and mobile TV as well. So, is it the next big thing? Believe it or not, you likely have digital TV already, possibly several of them. And you may not even realize it. In fact, the number of digital TV sources continues to climb, as does the number of...

The switching amplifier, or class D amplifier, has risen quickly to prominence in consumer audio applications, from MP3 devices including mobile phone handsets to games consoles, LCD-TVs, and home cinema. The ace in the deck for class D is its vastly superior efficiency, which can be as high as 85 to 90% in practice. A linear class-AB implementation will usually achieve around 25% at typical listening levels. In handheld applications, the low power dissipation of class D allows...