Analog Hotspot

A long-sought goal, room-temperature superconductors, may be a step closer to reality thanks to joint research by University of California scientists at the Los Alamos National Laboratory in New Mexico and researcher Yunkyu Bang of Chonnam National University in South Korea. The scientists have discovered that magnetic fluctuations in plutonium cobalt pentagallium (PuCoGa5) appear to cause the material to become superconductive. Scientists hope this unconventional...

Changes in capacitance, or in a complex impedance, are the input for many control applications. For example, capacitive sensing measures gas pressure and liquid volume. It's also used in proximity and humidity detectors. Impedance sensing is used in electro-impedance spectrometry, corrosion analysis, and liquid-condition analysis in industrial applications as well as for analyzing biological samples in medical equipment. Digitizing these changes has typically involved designing some kind...

Capacitive sensors supply high accuracy at a relatively low cost. But system designers attempting to use them have been forced to first convert the capacitance to a voltage, then convert the voltage into the digital domain using a precision analog-to-digital converter (ADC). The complex circuit design, lengthy prototype evaluation, and demanding system test usually cause the designer to look for a different sensor. They often select one that's more expensive, less accurate, or...

A filter is a signal-processing component that removes unwanted parts of an input signal such as noise, extracts useful parts of an input signal lying within a certain frequency range, or reshapes the frequency spectrum of the input signal. Analog filters operate on analog or continuous signals, while digital filters operate on digital samples of a signal. An analog filter comprises electronic components like resistors, capacitors, and op amps. These filters are widely used in...

Current measurements are used in a variety of equipment for control or safety functions. Measuring the voltage drop across a low-value resistor is the most common method of measuring the current flowing in a circuit. The current flow through the load also flows through the RSENSE resistor, also known as a shunt resistor, which creates a voltage drop, VM, across the resistor. Figure 1 depicts two current-measurement approaches. Ammeters were...

Dear Bob: Regarding Jason Cook's question on eyelets.* I worked at Motorola in the '60s, when eyeleted pc boards were still being used. In the days before plated holes were common, eyelets did prevent foil from peeling when a board was repaired, and they were the only way to get vias on two-sided boards. The eyelets were specially designed "double funnel" and had to be inserted properly so the funnel would split on the top side to allow solder to wick up. But they...

A complementary family of PMBus-compliant digital power-control ICs for telecom and datacentric applications supports designs from the ac line to the point of load. Texas Instruments' Fusion Digital Power family comprises three product series. Two work together in a purely digital-control mode. The third can be used with more modest digital controllers, providing most of the benefits of digital power control while closing the control loop in the analog domain. The UCD9xxx...

Sometimes a lot of power is just right. Sometimes 200 hp in a car is a lot better than 100. Sometimes even 1 hp gets a bicycle up the hill quite fast. Yet a bicycle can cruise along at 6 or 8 mph with less than 0.1 hp. That's part of the elegance of the bicycle, as an extremely efficient mode of transportation. Yet by using external sources of power, I can go uphill much faster than I can by pedaling my bike. The dollars per mile can drop way down, if I count my time...

Linear motors, in which "forcers" propel themselves back and forth along straight guides or tracks, have a long history. Yet the ServoTube line of linear motors from Copley Controls breaks away from that history with several innovations that improve reliability and maintainability. Instead of the optical encoders most linear motors use, the ServoTube motors employ a Hall-effect position sensor, which is more rugged and doesn't require calibration. With the Hall sensor, the...

The MAX9476 generates six identical, buffered, low-voltage TTL outputs at 35.328 MHz, all synchronized with an 8-kHz input clock. Designed by Maxim Integrated Products, this clock chip targets ADSL/VDSL central-office linecards and telecom network systems. It can track the input reference within ±100 ppm. An additional low-jitter, 8-kHz clock output can be used as a reference clock for other parts of the system. This output also can automatically detect the absence of the 8-kHz...

The future of power supplies was one of the hot topics at the Applied Power Electronics Conference, March 6-10 in Austin, Texas. One rap session and two professional education seminars tackled the subject. While nobody offered a clear picture of what this future would be like, though, some reasonable conclusions could be drawn. For years, power supplies have been designed using analog circuit design techniques. "Digital" power supplies have been designed over the last...

Two low-voltage differential-signaling (LVDS) interface chips for automotive applications perform at up to 125° C, delivering up to 10 bits of digital data at 20 to 80 MHz over a single point-to-point differential interconnect in backplanes or cable. The SCAN921025H serializer and SCAN921226H deserializer also include integrated built-in self-test and JTAG. They embed the clock in the serial data stream, eliminating any clock-to-data and data-to-data skew problem. A synchronization...

The LSK170 junction FETs fit sensitive amplification applications. Also, they can be used as pin-for-pin replacements for Toshiba's 2SK170 and as improved functional replacements for InterFET's IF1320, IF1330, IF1331, and IF4500. They offer typical datasheet values of 22-ms forward transfer admittance and 1-nV/Hz at 1 kHz and 2-nV/Hz at 10-Hz voltage noise, with only 22 pF of input capacitance. The LSK170 comes binned in 2.6- to 60-mA, 6.0- to 12-mA, and 10- to 20-mA IDSS ranges. Those...

Three field-programmable analog-array (FPAA) starter kits can be obtained from the Download Center on Anadigm's Web site. They comprise a subwoofer signal conditioner, an audio phase shifter, and a low-frequency filter. The subwoofer conditioner kit presents three examples of signal-conditioning circuits, each with a subsonic filter, low-pass filter, and compressor. It's possible to dynamically control the filter corner frequencies and arbitrarily define compression characteristics. A...

The 16-V AD8230 zero-drift precision instrumentation amplifier can be used in instrumentation environments where ground potentials vary by several volts. It also replaces custom designs made from discrete zero-drift amps and resistors. According to its manufacturer, the amp is the industry's first zero-drift in-amp to operate at 16 V. It maintains better than 50 nV/°C offset drift from 40°C to 125°C. Its 110-dB (min) common-mode rejection ratio rejects line noise in...

The 16-bit LTC2606 digital-to-analog converter (DAC) comes in a 3-mm2 DFN package with an I2C interface and 27 user-selectable slave addresses. As a result, many DACs can use the same bus while minimizing address conflicts with other components. Its guaranteed monotonic performance makes it useful for digital calibration, trim/adjust, and level-setting applications in a wide variety of products. The DAC's 2.7- to 5.5-V supply range draws a 270-µA operating...

Analog-to-digital-converter (ADC) resolution and sampling rates keep pushing the envelope. And every time they push further, it gets harder to match the ADC to an input amplifier in high-end test and measurement, medical imaging, wireless infrastructure, and industrial applications. So to meet the needs of ADCs reaching 100-MHz speeds, Texas Instruments came up with a third fully differential amplifier that uses the company's complementary-bipolar Bicom-III silicon-germanium (SiGe)...

Point 1: Cell-phone basestations now handle multiple interface standards in multicarrier implementations with faster data rates. Point 2: Wireless broadband promises furious access speeds and multimedia distribution. Combine the two points, and it becomes obvious that data converters are vital to achieving successful products. Analog-to-digital and digital-to-analog converters (ADCs and DACs) are used in a basestation's IF section. More and more, they're translating...

Hello Bob: I am looking for professional opinions/experiences regarding pc-board assembly using eyelets. I was told by Sam Reaves that you had written on the subject and could probably offer some good information. The problem that I am facing is that we are using eyelets on some pc boards in an effort to make the joints stronger. But I have seen some failures that are due to the eyelets. I need information to lead me to the correct decision and to use to convince others....

What's the relationship between jitter, phase noise, and signal-to-noise ratio (SNR) in data converters? Clock jitter is a problem in data conversion because it introduces uncertainty (noise) into the conversion process. Jitter in the time domain is equivalent to phase noise in the frequency domain. Phase noise spreads some of the clock's power away from its fundamental frequency. This is significant because sampling can be equivalent to mixing or...