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Circuit Cellar's editorial team comprises professional engineers, technical editors, and digital media specialists. You can reach the Editorial Department at editorial@circuitcellar.com, @circuitcellar, and facebook.com/circuitcellar

COMSOL Multiphysics 5.0 and the Application Builder

COMSOL recently announced the availability of Multiphysics 5.0 and Application Builder, with which “the power and accuracy of COMSOL Multiphysics is now accessible to everyone through the use of applications.”

Image made using COMSOL Multiphysics and is provided courtesy of COMSOL

Image made using COMSOL Multiphysics and is provided courtesy of COMSOL

According to COMSOL, Version 5.0 includes severral numerous enhancements to the existing Multiphysics software. The COMSOL Multiphysics product suite includes “25 application-specific modules for simulating any physics in the electrical, mechanical, fluid, and chemical disciplines.”

  • Multiphysics – Predefined multiphysics couplings, including Joule Heating with Thermal Expansion; Induction, Microwave, and Laser Heating; Thermal Stress; Thermoelectric and Piezoelectric Effect; and more.
  • Geometry and Mesh – You can create geometry from an imported mesh and call geometry subsequences using a linked subsequence.
  • Optimization and Multipurpose – The Particle Tracing Module includes accumulation of particles, erosion, and etch features. Multianalysis optimization was added as well.
  • Studies and Solvers – Improvements were made for the simulation of CAD assemblies, support for extra dimensions, and the ability to sweep over sets of materials and user-defined functions. Improved probe-while-solving and more.
  • Materials and Functions – Materials can now be copied, pasted, duplicated, dragged, and dropped. Link to Global Materials using a Material Link when the same material is used in multiple components.
  • Mechanical – Model geometrically nonlinear beams, nonlinear elastic materials, and elasticity in joints using the products for modeling structural mechanics.
  • Fluid – Create automatic pipe connections to 3-D flow domains in the Pipe Flow Module. The CFD Module is expanded with two new algebraic turbulence models, as well as turbulent fans and grilles.
  • Electrical – The AC/DC Module, RF Module, and Wave Optics Module now contain a frequency- and material-controlled auto mesh suggestion that offers the easy, one-click meshing of infinite elements and periodic conditions. The Plasma Module now contains interfaces for modeling equilibrium discharges.
  • Chemical – The Chemical Reaction Engineering Module now contains a new Chemistry interface that can be used as a Material node for chemical reactions.

Source: COMSOL

 

The World Is Analog

The world we live in is analog. We are analog. Any inputs we can perceive are analog. For example, sounds are analog signals; they are continuous time and continuous value. Our ears listen to analog signals and we speak with analog signals. Images, pictures, and video are all analog at the source and our eyes are analog sensors. Measuring our heartbeat, tracking our activity, all requires processing analog sensor information.

Computers are digital. Information is represented with discrete time and amplitude quantized signals using digital bits. Such representation lends itself to efficient processing and long-term storage of signals and information. But information and signals come from the physical world and need to move back into the physical world for us to perceive them. No matter how “digital” our electronic devices get, they always require interfaces that translate signals from the physical world into the digital world of electronics.

Even when computers talk to computers, analog interfaces are required. To transmit information over long distances (e.g., over a high-speed bus between the memory and the processor or over a wired network connection), the digital information needs to be moved into an analog format at the transmitter to drive the communication channel. At the receiver, the signals typically picked up from the channel do not look anymore like digital signals and need to be processed in the analog domain before they can be converted back into digital information. This is even more so if we consider wireless communications, where the digital information needs to be modulated on a high-speed radio-frequency (RF) carrier in the transmitter and demodulated at the receiver. RF electronics are also analog in nature.

The semiconductor industry has lived through tremendous advances fueled by what is known as Moore’s law: about every two years, thanks to increasing device miniaturization, the number of devices on a chip doubles. This exponential scaling has led to unprecedented advances in computing and software and has made the digitization of most information possible. Our literature, music, movies, and pictures are all processed and stored in digital format nowadays. Digital chips make up most of the volume of chips fabricated and it is thus economically desirable to fine-tune CMOS technologies for digital circuits. But electronic systems need analog interfaces to connect the bits to the world and most consumer products now rely on System-on-Chip (SoC) solutions where one integrated circuit contains the whole system function, from interfaces to digital signal processing and memory blocks. SoCs need a lot of analog interfaces, but their area is mainly composed of digital blocks (often over 90%). As technology scales, the performance of the digital core improves and this in turn increases the requirements of the analog interfaces.

Today’s analog designers are thus asked to design more interfaces with higher performance but using circuits that are as compatible with digital circuits as possible. This trend emerged a few decades ago and has grown stronger and stronger driven by the continuing increase of the functional density of SoCs. Not only do SoCs need more interfaces and better interfaces, the analog performance of highly miniaturized devices like nanometer CMOS transistors has steadily degraded.
 

This essay appears in Circuit Cellar #292 November 2014. 

 
Making nanoscale transistors is great to increase the functional density, but has its drawbacks when designing analog circuits. Nanoscale transistors can only withstand small supply voltages. For example, circuits designed with the latest CMOS transistors can only work with a supply voltage of up to 1 V or so. Traditionally analog circuits operated from voltages as large as +5 V/–5 V, but steadily their supply voltage was forced to reduce to 5 V, to 3.3 V, to 1.8 V, to 1.2 V and projections for future devices are as low as 0.5 V or even 0.2 V since reducing supply voltages also helps digital designs reduce energy consumption. However, for analog circuits, reducing the supply voltage increases their susceptibility to noise or interference and degrades signal quality. To add to the difficulties, nanoscale transistors also exhibit more mismatches, leading to random offset errors, more flicker (1/f) noise, and have poor gain performance.

But analog designers always like to rise up to a challenge. Research in academic and industrial groups has devised a number of novel analog design techniques to build better analog circuits while relying less and less on the performance of an individual device. In my group, for example, we have developed a set of design techniques to design analog circuits that operate with supplies as low as 0.5 V.

Scaling also offers new avenues for designing analog circuits. In nanoscale processes transistors are not able to handle large voltages, but they can intrinsically switch very fast. That allows us to introduce different signal representations at the transistor level for analog functions. Instead of using the traditional voltages or currents, we can now use time delays to represent analog information. This opens a whole range of opportunities to explore new circuits. Technology scaling is driving a paradigm shift in analog design away from the transistor used as a current source or voltage-controlled current source towards the transistor used as a fast switch even when processing analog information. In fact, analog circuits are being built out of what traditionally are digital blocks like switches or ring oscillators. But with the appropriate signal representation and circuit arrangements, they can process analog information to provide interfaces between the real world and the digital world.

The analog electronics field is going through very exciting times. The digital revolution in electronics has made analog even more necessary. And the future is looking bright. Mobile devices are packed with analog interfaces and a host of analog sensors, whose count increases with each new generation. The Internet of Things is all about massively gathering sensor information in one form of another, under strict power-consumption and cost constraints. All this while the traditional analog design techniques are clearly showing their limitations in the face of aggressive device scaling. This makes for a very challenging but a very interesting time for analog designers with plenty of opportunities to make an impact. Analog is the future!

KingetTTFPeter Kinget is a Professor of Electrical Engineering at Columbia University in New York. He received his engineering and PhD degrees in Electrical Engineering from the Katholieke Universiteit in Leuven (Belgium). His research group focusses on the design of analog and RF integrated circuits in scaled technologies and the novel systems or applications they enable in communications, sensing, and power management. (For more information, visit www.ee.columbia.edu/~kinget.)

 

WillowTree Apps Named Microchip Design Partner

Microchip Technology recently announced its first App Developer Specialist—WillowTree Apps—the latest company to join its Design Partner Network. WillowTree is an iOS, Android, and Mobile Web app developer that enables Microchip’s customers to focus on Internet of Things (IoT) designs.MicrochipWillowTree

WillowTree wrote the first mobile app for Microchip’s Wi-Fi Client Module Development Kit 1, which is available in the Apple App Store. It enables customers to quickly get up and running with the kit’s cloud-based demo. WillowTree can also modify this cloud-demo app to suit a broad range of customer IoT design requirements.

Source: Microchip Technology

Small High-Current Power Modules

 

Exar Corp. recently announced the 10-A XR79110 and 15-A XR79115 single-output, synchronous step-down power modules. The modules will be available in mid-November in RoHS-compliant, green/halogen-free, QFN packages.

In a product release, Exar noted that “both devices provide easy to use, fully integrated power converters including MOSFETs, inductors, and internal input and output capacitors.”

The modules come in compact 10 x 10 x 4 mm and 12 x 12 x 4 mm footprints, respectively. The XR79110 and XR79115 offer versatility to convert from common input voltages such as 5, 12, and 19 V.

Both modules feature Exar’s emulated current-mode COT control scheme. The COT control loop enables operation with ceramic output capacitors and eliminates loop compensation components. According to Exar documentation, tthe output voltage can be set from 0.6 to 18 V and with exceptional full range 0.1% line regulation and 1% output accuracy over full temperature range.

The XR79110 and XR79115 are priced at $8.95 and $10.95, respectively, in 1,000-piece quantities.

Source: Exar Corp.

Bluetooth Low Energy (BLE) Module Featuring smartBASIC

Laird Technologies recently announced the BL620 Bluetooth Low Energy (BLE) module, which is the newest edition to its BL600 series. Although it uses the BL600 hardware, the BL620 “has a new firmware load supporting Central mode connectivity,” Laird noted in its product release.”The BL620 makes it easy to add single-mode Bluetooth Low Energy (BLE), or Bluetooth Smart, to small, portable, power-conscious devices, including those powered by AAA or coin cell batteries.”LairdBL620_140px

Key features:

  • Event-driven smartBASIC programming language, which significantly simplifies BLE integration.
  • Reduces the engineering burden and design risk of integrating Bluetooth and BLE to a device.
  • Fully approved programmable
  • Compact footprint, low-power

If you already have a BL600 development kit, you can download the BL620 firmware and test it. You can download the BL620 firmware file from the Laird Bluetooth Firmware Download Center.

Source: Laird Technologies

Single-Board, Arduino Uno Shield-Compatible Dev Kit

Nordic Semiconductor’s new Arduino Uno shield-compatible nRF51 DK development kit supports Bluetooth Smart, ANT, and 2.4-GHz designs. Nordic also announced the availability of its nRF51 Dongle, which is a 16 mm × 28 mm USB dongle for the testing, analysis, and development of Bluetooth Smart, ANT, and 2.4-GHz applications.Nordic-nRF51 DK_1

The nRF51 DK is based on Nordic’s nRF51 Series SoC, which combines a 2.4-GHz multiprotocol radio, 32-bit ARM Corte M0 processor, flash memory, and 16- or 32-KB RAM. The SoCs can support a wide range of peripherals and are available in quad flat no-lead (QFN) and wafer level chip scale package (WLCSP) options.

Key points about the nRF51 DK and nRF51 Dongle

  • You can use the nRF51 DK with a variety of third-party Arduino shield expansion boards. It also supports ARM mbed for rapid prototyping projects.
  • The nRF51 DK allows access to all device peripherals, interfaces, and I/Os.
  • The nRF51 DK includes four user-programmable buttons and LEDS plus voltage and current pins to measure device power consumption.
  • nRF51 DK and nRF51 Dongle are supported by standard tool-chain options including Keil, IAR, and Gnu Compiler Collection (GCC).
  • The 63 mm × 101 mm nRF51 DK includes a coin-cell battery holder for field testing
  • You can use nRF51 DKhe DK as a programmer for other target boards that use the nRF51 Series SoC.

The nRF51 DK costs $69. The nRF51 Dongle is $49.

Source: Nordic Semiconductor

WIZnet Distinctive Excellence IoT Projects

The Circuit Cellar team felt strongly that there were considerably more first-rate projects entered in WIZnet Connect the Magic 2014 Design Challenge than could be satisfied with the available prizes. Thus, it designated a special category called “Distinctive Excellence” for some of the more interesting projects. The Distinctive Excellence projects are now live on the challenge website.wiznetDEs

Sponsor: WIZnet

New Digitally Enhanced Power Analog Controllers

Microchip Technology recently announced its latest Digitally Enhanced Power Analog (DEPA) controllers—the MCP19118 and MCP19119—which offer analog PWM control for DC-DC synchronous buck converters up to 40 V with the configurability of a digital microcontroller. MicrochipMCP19118

Interestingly, the devices bring together 40-V operation and PMBus communication interfaces for power-conversion circuit development with an analog control loop that is programmable in the integrated 8-bit PIC core’s firmware.  According to Microchip in a product release, “this integration and flexibility is ideal for power-conversion applications, such as battery-charging, LED-driving, USB Power Delivery, point-of-load and automotive power supplies.”

As expected, Microchip’s MPLAB X, PICkit 3, PICkit serial analyzer, and MPLAB XC8s support the MCP19118/9 DEPA controllers. The MCP19118 and MCP19119 are now available with prices starting at $2.92 each in 5,000-unit quantities.

 

High-Bandwidth Oscilloscope Probe

Keysight Technologies recently announced a new high-bandwidth, low-noise oscilloscope probe, the N7020A, for making power integrity measurements to characterize DC power rails. The probe’s specs include:

  • low noise
  • large ± 24-V offset range
  • 50 kΩ DC input impedance
  • 2-GHz bandwidth for analyzing fast transients on their DC power-rails KeysightN7020A

According to Keysight’s product release, “The single-ended N7020A power-rail probe has a 1:1 attenuation ratio to maximize the signal-to-noise ratio of the power rail being observed by the oscilloscope. Comparable oscilloscope power integrity measurement solutions have up to 16× more noise than the Keysight solution. With its lower noise, the Keysight N7020A power-rail probe provides a more accurate view of the actual ripple and noise riding on DC power rails.”

 

The new N7020A power-rail probe starts at $2,650.

Source: Keysight Technologies 

New M2M Wi-Fi Module

Lantronix’s xPico Wi-Fi SMT embedded device server is a “certified, compact Wi-Fi surface-mount module which enables quick and easy serial-to-Wi-Fi connectivity.” The module is intended for engineers interested in creating innovative Internet of Things (IoT) applications and solutions, especially designs that need “direct access to device data via smartphone, tablets, and connected PCs,” Lantronix noted in a product release.Lantronix-xPico

xPico Wi-Fi SMT features:

  • Surface Mount
  • On-board Antenna
  • u.fl Antenna Option
  • 18.3 mm × 31.1 mm × 3 mm Form Factor

Source: Lantronix

Twin-T Oscillator Configuration

Since retiring in 2013, electrical engineer Larry Cicchinelli has provided technical support at an educational radio station. For audio circuit debugging and testing, he uses a DIY battery-powered oscillator/volume unit (VU) meter. Details follow.

Originally, I was only going to build the audio source. When I thought about how I would use the unit, it occurred to me that the device should have a display. I decided to design and build an easy-to-use unit that would combine a calibrated audio source with a level display. Then, I would have a single, battery-powered instrument to do some significant audio circuit testing and debugging.

The front panel of the oscillator/volume unit (VU) meter contains all the necessary controls. (Source: L. Cicchinelli)

The front panel of the oscillator/volume unit (VU) meter contains all the necessary controls. (Source: L. Cicchinelli)

Cicchinelli describes the Twin-T Oscillator:

The oscillator uses the well-known Twin-T configuration with a minor modification to ensure a constant level over a range of power supply voltages. The circuit I implemented maintains its output level over a range of at least 6 to 15 V. Below 6 V, the output begins to distort if you have full output voltage (0 dBu). The modification consists of two antiparallel diodes in the feedback loop. The idea came from a project on DiscoverCircuits.com. The project designer also indicates that the diodes reduce distortion.

Figure 1 shows the oscillator’s schematic. Header H1 and diode D1 enable you to have two power sources. I installed a 9-V battery and snap connector in the enclosure as well as a connector for external power. The diode enables the external source to power the unit if its voltage is greater than the battery. Otherwise the battery will power the unit. The oscillator draws about 4 mA so it does not create a large battery drain.

The standard professional line level is 4 dBu, which is 1.228 VRMS or 3.473 VPP into a 600-Ω load. The circuit values enable you to use R18 to calibrate it, so the maximum output can be set to the 4-dBu level. A 7.7 (3.473/0.45) gain is required to provide 4 dBu at the transformer. Using the resistors shown in Figure 1, R18 varies the gain of U1.2 from about 4.3 to 13.

The Twin-T oscillator’s circuitry

Figure 1: The Twin-T oscillator’s circuitry

You may need to use different resistor values for R18, R19, and R20 to achieve a different maximum level. If you prefer to use 0 dBm (0.775 VRMS into 600 Ω) instead of 4 dBu, you should change R20 to about 5 kΩ to give R18 a range more closely centered on a 4.87 (2.19/0.45) gain. The R20’s value shown in Figure 1 will probably work, but the required gain is too close to the minimum necessary for comfort. Most schematics for a Twin-T oscillator will show the combination of R3 and R4 as a single resistor of value Rx/2. They will also show the combination of C1 and C2 as a single capacitor of value Cx × 2. These values lead to the following formula:

CicchinelliEQ1

As you can see in the nearby photo, the Twin-T Oscillator and VU meter contain separate circuit boards.

The Twin-T oscillator and dual VU meter have separate circuit boards

The Twin-T oscillator and dual VU meter have separate circuit boards

This article first appeared in audioXpress January 2014. audioXpress is one of Circuit Cellar‘s sister publications.

 

Dev Platform with 2-D Multi-Touch and 3-D Gestures

Microchip Technology recently announced the availability of the 3DTouchPad, which it describes as “a PC peripheral and world’s first Development Platform for 2D multi-touch and 3D gestures.”Microchip_3DTOUCH_7x5_RGB

The 3DTouchPad adds free space gesture recognition to projected-capacitive multi-touch.  Basically, it provides 3-D gesture recognition via Microchip Technology’s GestIC, which provides a detection range of up to 10 cm for 3D gestures, as well as Microchip’s projected-capacitive 2-D multi-touch solution supporting up to 10 touch points and multi-finger surface gestures. Microchip also claims the 2-D multi-touch is enhanced by its new capacitive touch-screen line driver, MTCH652.

The new 3DTouchPad includes: a driverless, out-of-the-box features for Windows7/8.X and OS X, 3D air gestures; advanced multi-touch performance including surface gestures; and a free downloadable GUI and SDK/API package. Possible applications include home automation, remote controls, game controllers, and wearable devices.

The 3DTouchPad costs $99.

Source: Microchip Technology

Ultra-Low-Power 10-Bit Hall Encoder

iC-Haus’s iC-TW11 is an ultra-low-power, single-chip Hall encoder that enables energy-saving 10-bit angle detection. As a result, it is a good solution for battery-buffered applications.

iC-Haus TW11 encoder

iC-Haus iC-TW11 encoder

The encoder’s sampling rate of 10 Hz yields an average current consumption of typically 3 µA. In Standby mode between measuring cycles, the idle current cuts back to approximately 100 nA. In normal operation, the encoder supports sampling rates of 4 kHz with an activated filter and automatic amplifier gain for 10-bit resolution at maximum accuracy. A measuring cycle operates via either a SPI or a separate trigger input by an external event.

The  iC-TW11 EVAL TW11_1C evaluation board comes with a USB interface and GUI software. At a voltage supply of 3.3 V (+/-10 %), the iC-TW11 operates in an extended industrial operating temperature range from –40° to +125°C.

Production volume pricing starts at $4.21 in 1,000-piece quantities.

Source: iC-Haus

 

 

Linear Battery Charger with Multi-Chemistry Operation

Linear Technology Corp. recently introduced the LTC4079, which is a 60-V, constant-current/constant-voltage, 250-mA multi-chemistry battery charger. According to Linear, its “low quiescent current linear topology offers a simple inductorless design and accepts a wide 2.7 V to 60 V input voltage range.”LinearLTC4079

 

The LTC4079’s features, characteristics, and capabilities include:

  • A resistor-programmable 1.2- to 60-V battery charge voltage range with ±0.5% charge voltage accuracy
  • Adjustable charge current from 10 to 250 mA with an external resistor
  • A low-profile (0.75 mm) 10-pin 3 mm x 3 mm DFN package with backside metal pad for excellent thermal performance.
  • Guaranteed foperation from –40°C to 125°C in both E-and I-grades.
  • One thousand-piece pricing starts at $2.35 each for the E-grade.

Source: Linear Technology

Read Your Technical Documentation (EE Tip #145)

Last year we had a problem that showed up only after we started making the product in 1,000-piece runs. The problem was that some builds of the system took a very long time to power up. We had built about 10 prototypes, tested the design over thousands of power ups, and it tested just fine (thanks to POC-IT). Then the 1,000-piece run uncovered about a half-dozen units that had variable power-up times—ranging from a few seconds to more than an hour! Replacing the watchdog chip that controlled the RESET line to an ARM9 processor fixed the problem.

But why did these half dozen fail?

Many hours into the analysis we discovered that the RESET line out of the watchdog chip on the failed units would pulse but stay low for long periods of time. A shot of cold air instantly caused the chip to release the RESET. Was it a faulty chip lot? Nope. Upon a closer read of the documentation, we found that you cannot have a pull-up resister on the RESET line. For years we always had pull-ups on RESET lines. We’d missed that in the documentation.

Like it or not, we have to pour over the documentation of the chips and software library calls we use. We have to digest the content carefully. We cannot rely on what is intuitive.

Finally, and this is much more necessary than in years past, we have to pour over the errata sheets. And we need to do it before we commit the design. A number of years ago, a customer designed a major new product line around an Atmel ARM9. This ARM9 had the capability of directly addressing NOR memory up to 128 MB. Except for the fact that the errata said that due to a bug it could only address 16 MB. Ouch! Later we had problems with the I2C bus in the same chip. At times, the bus would lock up and nothing except a power cycle would unlock it. Enter the errata. Under some unmentioned conditions the I2C state machine can lock up. Ouch! In this case, we were able to use a bit-bang algorithm rather than the built-in I2C—but obviously at the cost of money, scheduling, and real time.—Bob Japenga, CC25, 2013