Analog Hotspot

Ceramic and piezoelectric speakers feature very low dissipation losses and compact size. They're an attractive alternative to moving-coil speakers in applications ranging from flat-screen TVs and monitors to cell phones. Their low dissipation arises from the nature of the load they represent, which is essentially capacitive. Typical values (depending on speaker size) range from 20 to 3000 nF. Driving a piezoelectric speaker requires an amplifier that can handle such loads...

A filter-free stereo class D audio power amp from Texas Instruments maximizes cell-phone talk time and audio quality. With about two-thirds lower quiescent current and 80% lower noise floor than its nearest competitor, the TPA2012D2 is a 2.1-W stereo class D audio power amplifier housed in a 4- by 4-mm ThinQFN. It operates from a 3.3-V supply, draws 6 mA, and has a 27-mVRMS A-weighted noise floor. Available now, it costs $0.95 in quantities of 1000. A lead-free 2- by 2-mm...

There are many comparators that you can buy to provide quick (sub-microsecond) response when a large signal changes and crosses a threshold voltage, such as a reference voltage. Unfortunately, comparators don't work well when the input signals are very small. The ability to respond correctly, without offset, drift, or noise, is normally impossible to do with a comparator unless the signal is moving more than a millivolt beyond the reference voltage. And with a comparator, you can't add a...

According to recent industry data, analog/mixed-signal and RF content occupies some 5% to 10% of the area of an increasing number of systems-on-a-chip and systems-in-a-package. However, that percentage alone can chew up 50% of the design effort and trigger 50% of the re-spins. To address the need for productivity and silicon accuracy, Cadence has rolled out new capabilities under its Virtuoso custom design platform. Analog/mixed-signal and RF designers face core challenges...

Analog engineers are in short supply. Yet IC makers prudent enough to have substantially invested in analog EEs, particularly those who can straddle the digital and analog domains, are using their talents to win business with consumer-products OEMs and to lock out competitors. More and more, these efforts are making themselves evident in chips that require a minimum of experience in analog layout and interfacing coupled with accompanying reference designs that more or less...

A new process technology allows system designers to avoid adding external signal conditioning, signal biasing, and external op amps in industrial-control and medical applications. Analog Devices calls this process iCMOS, and the company has used it to launch a 15-chip family. An iCMOS chip can mix and match 5-V CMOS elements with higher-voltage 16-, 24-, or 30-V CMOS circuitry. The resulting products combine small size, low power, and high performance. The...

Rather than waste months of engineering time on tricky applications with low to moderate production volumes—like digital X-ray equipment, digital telescopes, military imaging, and sonar and radar—try an off-the shelf analog-to-digital converter (ADC). Datel's ADSD-1410 dual, 14-bit, 10-MHz, sampling ADC features buffered outputs as well as two 30-MHz sample-and-hold amplifiers and two independently clocked, 14-bit, 10-Msample/s ADCs. An ASIC provides timing and...

Historically, amplifier class designations seemed to be related to how amplifier devices were biased—that is, the percentage of the input-signal swing over which they conducted. That worked for classes A, B, AB, and C. Today, class designators can only tell us how recently a new class was invented. Here is the current lineup of audio-amplifiers: Class A: single-ended; amplifier device is biased about the center of the input-signal...

Conventional wisdom has it that class D amplifiers occupy an applications niche in which efficiency is paramount, and that several factors compromise sound quality. The latter includes difficulty in implementing feedback, mediocre power-supply rejection ratio (PSRR), and the drawbacks of constant switching-frequency pulse-width modulators (PWMs). Countering the conventional wisdom, Analog Devices (ADI) integrated a delta-sigma modulator with its AD1991 class D...

Hi, Bob: I have a problem and could use your help. It initially sounded easy to me, but proved not so. I need to find an analog circuit for the following problem: I have 13 resistors with different values. I know the list of values and need to randomly pick two resistors from those 13 to put into the circuit. The circuit should be able to tell me which one is the larger resistance value. If possible, please provide some advice on this problem that has puzzled me for a...

I was walking down a hallway on the top floor of NSC's building D, when something I heard made me suspicious. It sounded like a series of tiny clicks rattling around the hallway. I stopped and slapped my thigh to make a sharp sound. I heard TICK-TICK, tick-tick, tick-tick. I was surprised, because there was no obvious reason why this hallway should do this. It even had a carpeted floor. I tried the slap in several other hallways—and in tile bathrooms—and got almost none of this...

A phase-locked loop (PLL) is pretty basic. How much can one IP vendor's PLL differ from another's? While the high-level PLL schematic is simple, the simplest PLLs don't perform well. They all accept a reference clock and generate another clock, frequency multiplied and/or phase-locked to the reference. Yet PLLs from different IP vendors offer different features, flexibility, and output quality. The right PLL can make the design of the clocking system easier and more...

By building in more value-added features, companies hope to remove some of the hocus-pocus from the analog-design portions of new products. Obviously, these features can't instantly move OEM customers to the cutting edge of performance. But they're preventing the more predictable design errors that tend to scuttle schedules when a ones-and-zeros engineer tries to implement something with voltages that insist on wriggling around. These value-added features are embedded in the...

Expert designers are hard to find. So, converter suppliers are making their products easier to use. Some suppliers simplify analog front-end design by choosing alternative architectures. Delta-sigma, both switched-capacitor and continuous-time, simplifies front-end filtering compared to successive-approximation registers (SARs) and pipelines. Another trend sees amplifiers custom-designed for targeted converters. Alternatively, variable-gain amplifiers (VGAs) are being built into the...

Two major trends will dominate digital-to-analog converters (DACs) this year. First, competition will intensify to even greater heights thanks to strides made in consumer audio in your home, car, and pocket. Second, DACs for communications systems, where they operate in the transmit chain, are virtually evolving into modulation subsystems while eliminating a few upconversion stages in the process. AUDIO As in other types of analog and...

The most conspicuous trend in amplifiers is the list of new features that help systems engineers who aren't entrenched analog specialists avoid catastrophic design errors. Consider how it demolishes a system-development schedule when an amplifier that worked perfectly on the bench does nothing but oscillate on the prototype project board. Suppliers have designed more bulletproof amplifiers and created GUI-based design tools so those amplifiers are more apt to behave themselves in real...

If you're an experienced analog designer, today's laws of supply and demand mean that you're a hot property. On the other hand, if you're a system designer, you'd probably like to get some well-seasoned analog designers in your group. If you're an engineering student, well, that's something to think about. But becoming an analog engineer isn't just a matter of signing up for the right courses. I got an array of responses when I asked engineers at various companies how they...

With speeds clocking hundreds of times faster than the first commercially available IC op amps, today's high-speed amplifiers cost less and consume less power than their predecessors. This evolution may be the best indicator of what's to come for amplifiers. Significant advances in process technology-specifically, complementary bipolar processes that enable gigahertz speeds-make it possible for amplifiers to deliver more performance at lower cost and higher power efficiencies...

Reliable operation at -40°C to 125°C used to be considered high-rel. But auto makers want no worse than one defective part in a million components that are shipping at rates of more than a million per month. Thus, auto makers are demanding and getting more reliability than the military ever required. To meet the old high-rel standards, chip makers depended on packaging and screening. Today, where using ordinary process technologies and packaging, the key lies in the design,...

Although the product described here is an ASSP rather than an enhanced amplifier, I must note that an obvious potential new application area for driving Ethernet cable is parallel 10-Gigabit Ethernet. Last summer, a startup called SolarFlare Communications demonstrated a high-performance integrated analog front end for handling 10-Gbase-T transmission over copper. The company's AFE integrated four 10-bit, 1-Gsample/s ADCs, each with a dedicated programmable gain amp and PLL. A...