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Яка роль корпоративної етики та культури в антикорупційній сфері? kpi ср, 06/11/2025 - 12:34

BluGlass Ltd of Silverwater, Australia — which develops and manufactures gallium nitride (GaN) blue laser diodes based on its proprietary low-temperature, low-hydrogen remote-plasma chemical vapor deposition (RPCVD) technology — has extended the closing date for its share purchase plan (SPP) offer (which opened on 8 May) from 10 June to 17 June...

MACOM Technology Solutions Inc of Lowell, MA, USA has announced the availability of a wideband front-end module (FEM) covering 2–18GHz. Suitable for electronic countermeasures (ECM) and phased-array radar applications, the miniature multi-chip ENGSD00088 transmit/receive module integrates a high-power 3-stage gallium nitride (GaN) power amplifier (PA), a 3-stage gallium arsenide (GaAs) low-noise amplifier (LNA) and a transmit/receive (T/R) switch with a fail-safe antenna termination, all within a compact package...

New MCUs Are Ideal for Portable Devices such as Data Loggers and Charge Cases

Renesas Electronics Corporation, a premier supplier of advanced semiconductor solutions, introduced the RA2L2 microcontroller (MCU) group with ultra-low power consumption and the industry’s first support for the new UCB-C Revision 2.4 standard. Based on a 48-MHz Arm Cortex M23 processor, the new MCUs offer a rich feature set that makes them ideal for portable devices and PC peripherals such as gaming mice and keyboards.

The new USB Type-C Cable and Connector Specification Release 2.4 has reduced voltage detection thresholds (0.613V for 1.5A source, and 1.165V for 3.0A source). The RA2L2 MCUs are the industry’s first MCUs to support these new levels.

The RA2L2 MCUs employ proprietary low-power technology that delivers 87.5 µA/MHz active mode and software standby current of just 250nA. They also offer an independent operating clock for the low-power UART, which can be used to wake up the system when receiving data from Wi-Fi and/or Bluetooth LE modules. Along with the USB-C support, this combination of features makes the RA2L2 the premier solution available for portable devices such as USB data loggers, charge cases, barcode readers and other products.

In addition to USB-C with CC detection up to 15W (5V/3A) and USB FS support, the new MCUs offer LP UART, I3C, and CAN interfaces, giving designers the ability to reduce component count, saving cost, board-space and power consumption.

The RA2L2 MCUs are supported by Renesas’ Flexible Software Package (FSP). The FSP enables faster application development by providing all the infrastructure software needed, including multiple RTOS, BSP, peripheral drivers, middleware, connectivity, and networking as well as reference software to build complex AI, motor control and cloud solutions. It allows customers to integrate their own legacy code and choice of RTOS with FSP, thus providing full flexibility in application development. The FSP eases migration of existing IP to and from other RA devices.

“The RA2L2 Group MCUs are our first to realize full-speed USB along with USB-Type C connector support. They also ensure system costs remain low by reducing external components, and they offer the same low-power characteristics as our popular RA2L1 devices,” said Daryl Khoo, Vice President of Embedded Processing Marketing Division at Renesas. “These new devices demonstrate our commitment and ability to quickly deliver the solutions our customers require.”

Key Features of the RA2L2 MCUs

• Core: 48 MHz Arm Cortex-M23
• Memory: 128-64 KB Flash, 16 KB SRAM, 4 KB Dataflash
• Peripherals: USB-C, USB-FS, CAN, Low Power UART, SCI, SPI, I3C, I2S, 12-bit ADC (17-channel), Low Power Timer, Real-Time Clock, High-Speed On-chip Oscillator (HOCO), Temp Sensor
• Packages: 32-, 48- and 64-pin LQFP; 32- and 48-pin QFN
• Security: Unique ID, TRNG
• Wide Ambient Temperature Range: Ta = -40°C to 125°C
• Operating Voltage: 1.6V – 5.5V; USB Operating Voltage: 3.0V to 3.6V

Winning Combinations

Renesas has combined the new RA2L2 MCUs with numerous compatible devices from its portfolio to offer a wide array of Winning Combinations, including USB Data Logger, Electronic Toll with GNSS, Gaming Keyboard and Gaming Mouse. These designs are technically vetted system architectures from mutually compatible devices that work together seamlessly to bring an optimized, low-risk design for faster time to market. Renesas offers more than 400 Winning Combinations with a wide range of products from the Renesas portfolio to enable customers to speed up the design process and bring their products to market more quickly.

The post Renesas Brings USB-C Rev. 2.4 Support to New Ultra-Low-Power RA2L2 Microcontroller Group appeared first on ELE Times.

🎭 КПІ Cos Fest — перший фестиваль гік-культури в КПІ ім.Ігоря Сікорського kpi вт, 06/10/2025 - 23:11

Efficient Power Conversion Corp (EPC) of El Segundo, CA, USA — which makes enhancement-mode gallium nitride on silicon (eGaN) power field-effect transistors (FETs) and integrated circuits for power management applications — has released the EPC9196, a high-performance 25ARMS, 3-phase brushless DC (BLDC) motor drive inverter reference design powered by the EPC2304 eGaN FET. The EPC9196 is specifically designed for medium-voltage (96V–150V) battery-powered motor drive applications, including steering systems in automated guided vehicles (AGVs), traction motors in compact autonomous vehicles, and precision motor joints in robotics...

I’m disassembling this speaker from 1999 to salvage components. Thought the moisture absorbing glue on the i/o panel was pretty neat. And get a load of those chonky 3300 uF capacitors! submitted by /u/tbone_man [link] [comments]

Sponsor Message: This cutting-edge solution efficiently manages heat generated by advanced AI processors and GPUs, ensuring optimal performance in complex electronic devices. Honeywell PCMs significantly enhance thermal performance, prevent component malfunctions, and mitigate particle issues. Connect with us to discover more about our PCMs that are engineered for improved thermal management in Automotive/EVs, AI servers, and consumer electronics.

Designing an analog circuit can be a frustrating experience, as noted by Nick Cornford in his Design Idea (DI), “DIY RTD for a DMM.” With a fortnight’s struggle, I completed the design of 4 mA to 20mA, two-wire temperature transmitter using a platinum resistance temperature detector (RTD) sensor, as shown in Figure 1.

Figure 1 A two-wire transmitter with a platinum RTD sensor, R4. R1 and R4 will determine the currents through the respective limbs; these currents must be kept to 0.5 mA. The circuit is designed to operate from 0 °C to 300 °C, where R5 can be adjusted to change this temperature range.

Wow the engineering world with your unique design: Design Ideas Submission Guide

In industrial processing applications, a two-wire topology is used to connect the temperature sensor in the field to the control room equipment, such as a distributed control system (DCS), programmable logic controller (PLC), or indicator. A 24-V DC supply is fed from the control room, and the current drawn is proportional to the temperature. Since the power and signal travel in the same pair of wires, this arrangement offers cable savings.

In Figure 1’s circuit, R4 is an RTD. As per the platinum RTD’s temperature versus resistance table (DIN EN 60751), R4 is 100 Ω at 0 °C and 212.2 Ω at 300 °C.

This circuit is designed for the range of 0 °C to 300 °C, where the load current will be 4 mA for 0 °C and 20 mA for 300 °C (you may change R5 to achieve other ranges). The current is proportional to the resistance of the RTD, which is slightly non-linear with respect to temperature. The accuracy claimed in this circuit is ±1%, which is adequate for many applications.

To avoid self-heating of the RTD, only 0.5 mA is sent through it. R1 and R2 must be adjusted to pass 0.5 mA in each limb. U1 and U4 are wired as zero tempco current sources. The difference in voltage between RTD (R4) and R3 is amplified in the instrumentation amplifier U3.

The RTD at 300 °C (or R4 at 212.2 Ω) sends 160 µA through R8. R10 sets the current through it as 40 µA. Hence, a total of 200 µA is sent as the input to the transmitter IC, U5.

U5 then amplifies this current by 100 to 20 mA and converts it into a two-wire format. The U2 circuit generates -3.3 VDC to feed the negative supply voltage pin of U3. Accurate results were only achieved when operating U3 with a dual supply. The RTD at 0 °C gives a 4-mA current at the output (LOAD).

Jayapal Ramalingam has over three decades of experience in designing electronics systems for power & process industries and is presently a freelance automation consultant.

Related Content

• DIY RTD for a DMM
• Two-wire interface has galvanic isolation
• Two-wire remote sensor preamp
• Designing with temperature sensors, part three: RTDs

The post A two-wire temperature transmitter using an RTD sensor appeared first on EDN.

Alphawave Semi is in the news after being acquired by Qualcomm for $4.2 billion, and so is its co-founder and CEO Tony Pialis, now widely seen as a semiconductor connectivity IP veteran. Here is a brief profile of Pialis, highlighting how the design of analog and mixed-signal semiconductors fascinated him early in his career and how this led to his work on DSP-centric SerDes architectures.

Read the full story at EDN’s sister publication, Planet Analog.

Related Content

• IP players prominent in chiplet’s 2024 diary
• Alphawave Semi’s quest for open chiplet ecosystem
• BoW Strengthens Pathway to Chiplet Standardization
• How the Worlds of Chiplets and Packaging Intertwine
• Why UCIe is Key to Connectivity for Next-Gen AI Chiplets

The post Tony Pialis’ design journey to high-speed SerDes appeared first on EDN.

Fake electronics fiascos

Until recently, at least to the best of my awareness and recollection, I’ve only been fooled into three purchases of counterfeit tech devices, all of which I’ve documented in past blog posts:

1. Hands-on review: Is a premium digital audio player worth the price? (Specifically note the mention within it of my acquisition of two fake-capacity 400GB microSD cards)
2. Memory cards: Specifications and (more) deceptions, and
3. USB activation dongles: Counterfeit woes

In the first and third cases, I should, in retrospect, have known better, since the devices I bought were substantially lower priced than equivalents from more “legitimate” seller sources. The second case was the seeming result of someone returning to Amazon a falsely labeled subpar substitute for something they’d bought, and Amazon not catching the switcheroo and reselling it as legit on the “Warehouse” area of their site. In all three cases, happily, I got my money back.

Mercari’s previous track record

This fourth time, unfortunately, I wasn’t so lucky. And the deception was, if anything. more impressive (among other, less-positive adjectives) than before. Mercari, for those of you not already familiar with it, is a Japan-based buyer/seller intermediary online service in the same vein as eBay or (for audio gear) Reverb. It’s generally considered to be more “seller-friendly” than eBay; how much so will become clear shortly. My first (recent) purchase there, which went smoothly and successfully, was of a headphone amplifier. I subsequently picked up a matching equalizer from the same manufacturer (Schiit Audio) via another seller, along with two Raspberry Pi AI Cameras and a special-edition Ray-Ban Meta AI Glasses set, the latter which will be showcased in another writeup (a pseudo-teardown, to be precise) this month. All went fine.

The sixth Macari-coordinated transaction? Not so fine. Perhaps, in retrospect, the prior track record lulled me into a false sense of complacency. More likely, I just “wanted to believe” too much, referencing the memorable X-Files poster- and character-delivered quote:

I’d been watching the for-sale postings of a seller with username “Skii” (apparently short for “skiitheflipper”) for a while. This person regularly listed claimed-legitimate and factory-sealed 2nd-generation Apple AirPods for sale, and Mercari dutifully let me know each time “Skii” lowered his sales price on the particular set I was watching. When they hit $93, I was seriously tempted. And when Mercari did a one-day free-shipping promotion, I bit. The total price, including sales tax and a $3.54 “buyer protection fee” (cue foreshadow snort), was $100.88.

A pause here for some background: first off, given that I already had both a primary and backup set of first-generation AirPods Pros, why was I interested in a second-generation set the first place, particularly with the AirPods Pro 3 rumored to arrive later this year? At the normal $249 price, I wasn’t. Even at the fairly common $189-or-thereabouts promotion price, I didn’t pull the trigger. But why the interest at all? The AirPods Pro 2, in comparison to the first-generation forebears I already owned, have claimed superior active noise cancellation, for example, along with dynamically adaptive “transparency” mode and longer battery life. More recent gen-2-only enhancements include the Hearing Aid feature, which I don’t require (at least I don’t think so! What did you say?) but still wanted to try. And the further temptation of possibly upcoming Live Language Translation pushed me over the edge…once the price tag dipped below $100, that is.

About that price…many of you are likely right now thinking something along the lines of “Were you really so stupid as to think that something sold at a roughly 2/3 discount to MSRP was legit?”. Actually, I wasn’t. Although, hey, who knows…per the “flipper” portion of the seller’s username, maybe he or she had scooped up the inventory of a going-out-of-business retailer and was reselling it. Regardless, I figured that I’d give the purchase a shot, and if it was a fake (as I assumed would be immediately obvious) I’d file a dispute and get my money back. Which was conceptually feasible, mind you. But as a Mercari newbie, I didn’t realize how difficult it would be, both in an absolute sense and in relative comparison to eBay (on which I’d been a regular participant since 1997), to translate the buyer-refund concept into reality. Hold that thought.

The listing 

Back to my story. To his credit, the seller at least was speedy from a delivery standpoint; the package shipped on Tuesday, April 1 (April Fool’s Day: how prophetic) and arrived that same Saturday. At first glance, at least to my uneducated-recipient’s eyes, everything looked authentic, although had I known more/better I never would have clicked on “buy” in the first place. Here are the photos that accompanied the listing:

Looks legit, right? Only one problem, I later learned: Apple reportedly no longer sells AirPods in shrink-wrapped boxes. But pretend for now that, like me at the time, you’re not aware of that critical nuance.

The delivery

Here’s the (shrink-wrap already removed) box of the actual product I received, as usual, accompanied by a 0.75″ (19.1 mm) diameter U.S. penny for size comparison purposes:

The tape strips at the top and the bottom were seemingly “stiffer” than I’d remembered before with other Apple devices, but I didn’t give that much thought, eager to get inside:

Getting the two halves of the box apart was similarly more difficult than I’d remembered …but again, I now have the benefit of hindsight in making these key-nitpick observations. The literature package up-top seemed to be legit:

The protective plastic sleeve around the case admittedly also seemed flimsier than I’d remembered from other Apple earbuds (there’s that rear-view-mirror perspective again):

Putting the case aside for a minute, let’s look at the rest of the contents (again, a reminder that these shots were taken post-initial removal). Extra earbud tip sizes:

And below them, an authentic-looking and functional (at least for charging) USB-C cable:

Now for that case. The LED in front seemingly operates as expected (both green and orange illumination mode options), as do the speakers and USB-C port on the bottom edge:

Open the case: it still looks, sounds (beep!), and otherwise acts legit.

Earbuds out: Charging contacts at the bottom of each receptacle.

The earbuds themselves, from various perspectives. Apologies for the earwax remnants

“That’s odd.” 

Back in the case for initial pairing, which is where my initial “that’s odd” moment happened (hold that thought for a possible explanation to follow shortly):

I didn’t recall this particular message before, particularly for supposedly brand-new Apple earbuds, but I plunged on and got them paired and associated with my Apple user account straightaway. They automatically also appeared in the paired-Bluetooth-devices listings of all my other Apple widgets. One thing that seemed a little strange upfront was that “Handoff” mode, wherein I could connect to them from another account-associated device even if they were connected to a different device at the time, didn’t seem to work. I instead needed to manually disconnect them from, for example, my iPad before I could connect them to my MacBook Pro. But after a bit of online research, I chalked that up to a potential bug with the earbuds’ current firmware version (7A305, which dated from late September 2024). And about that…check out the three-part post-activation settings listing:

All looks legit, right? The earbuds even claimed that valid warranty coverage existed through June 2025! Activating noise cancellation seemed to do something, although I can’t say it was notably superior (or even equivalent) to what I’d experienced with their first-generation forebears. And when I tried to activate hearing aid mode, it told me that I’d have to update the firmware before that particular feature was available for my use. All reasonable. When I tried “Find My” on them, it couldn’t locate them, but I figured that since I’d just activated them, Apple’s servers were just slow and they’d show up eventually. So, I connected them to my iPad, put them in close proximity to it so that the firmware would auto-update, and…

Mercari’s seller rating policy

Another background-info pause. As soon as USPS delivered the earbuds, Mercari as-usual sent email alerting me that they were at my front door and—this is key—immediately encouraging me to “rate the seller” so he or she could get paid. From past experience, those emails would continue at a one-to-multiple times-per-day cadence until I either reported a problem or went ahead and rated the seller. And here’s the twist that I didn’t realize until afterwards:

• The buyer has only 72 hours after package delivery to report a problem
• In the absence buyer response to the contrary after (only) 72 hours, Mercari goes ahead and automatically marks the package as received and pays the seller anyway (remember my earlier “seller-friendly” comment about the service?), and
• Once the transaction is complete, Mercari washes its hands (words ironically written by me within the Triduum) of the matter and accepts no further fiscal responsibility.

Did I go ahead and rate the seller that same evening so that he/she could get promptly paid? Bathed in the “giddiness glow” of a seeming legit transaction…yes, I did. Sigh. The next morning, of course, when I checked the settings and saw that the firmware had not updated, alarm bells belatedly started going off in my head. Multiple subsequent factory-reset and re-pairs were equally unsuccessful in getting the firmware updated. And then I found this video:

Different serial numbers on each earbud

wherein I remembered that although the serial number on the packaging matched that on the case and (by default) reported in settings, the serial numbers for the right and left earbuds were supposed to be different in both places. Here, for example, are the serial number markings on the case and earbuds for my first-generation AirPods Pros (apologies again for the earwax bits):

The print is a bit faint, but hopefully you can see that the serial numbers on the earbuds both don’t match those on the case (H6VHW8651059) and are different from each other (H6QHWQRX06CJ and H6VHX88Q0C6K).

Now here’s the settings listing entry of interest for the “fakes”. If you click on it, it’ll report unique serial numbers for the case and each earbud:

And the model numbers stamped on the case and both earbuds are also different, and match what they should be. But the stamped serial numbers on all three? Identical: DT601W1T41.

And are, I’m guessing, also identical to the serial numbers stamped on and reported by who-knows-how-many other identical “fakes” also sold by “Skii” and others, which is why I got the initial “not your” notification at the beginning of the pairing process. Apple, is it not possible to detect and more meaningfully alert owners when multiple sets of earbuds with identical serial numbers are activated? You have both fiscal and reputational motivations to do so, after all.

I’m begrudgingly impressed with the degree to which these counterfeit earbuds mimic the real thing. And here’s the twist: were I the owner of only a single Apple device, such as an iPhone, therefore unaware of the “Handoff” glitch, and were I a typical non-geeky (non-Brian) consumer, unaware how to determine the existing firmware version, far from what the current version is, how to update it and what it would add to my usage experience…I might be blissfully unaware far into the future that I’d bought a cheap-but-fake set of earbuds …maybe forever.

Reporting the fake to Mercari

I reported the situation in detail, complete with pictures, to Mercari. Throughout the subsequent email back-and-forth, they several times reminded me that:

When you submit a rating for your transaction, you are prompted to confirm you understand that once the rating is submitted, the sale is final. Once submitted, funds are released to the seller and we are no longer able to process a return or refund. Moving forward, if you receive an item that is not as described, please do not submit a rating for your seller and contact us immediately.

That said, they also made a promise:

Please know that if a report is made against the seller we will conduct an investigation to confirm the suspicions. If the seller is found guilty immediate action will be taken against them regarding their listings. I appreciate for your concerns and just for you we will further review this for you. Your case will be taken as a feedback and we do value your time in reaching out to us to inform us of this inquiry.

and:

Regarding your seller’s action, please note that our team is very vigilant with those kinds of activities. We will conduct monitoring where we will need to check all their transactions and make sure that our Trust and Safety team will review this concern. Please leave it to us, rest assured that the right sanction will be given accordingly.

It’s been two weeks since I filed my report. “Skii” is still on Mercari. And as I write these words, he or she has three more “authentic” AirPods Pro 2 sets for sale. Admittedly, “Skii” may not even know that the earbuds being sold are fakes. Although I doubt it. Caveat emptor, indeed.

Then there was this closing email from Mercari:

Thank you for reaching out to Mercari! We hope your issue was resolved to your satisfaction.

We would appreciate it if you could take a moment to provide us with your feedback. Your input helps us improve our service. Thank you for helping us serve you better!

Grrr.

I plan to “turn lemons into lemonade” via future teardowns of both the case and one of the earbuds, comparing them to existing published teardowns of legit alternatives. Until then, I welcome your thoughts in the comments on what I’ve written so far on this “fakes” saga.

—Brian Dipert is the Editor-in-Chief of the Edge AI and Vision Alliance, and a Senior Analyst at BDTI and Editor-in-Chief of InsideDSP, the company’s online newsletter.

Related Content

• Hands-on review: Is a premium digital audio player worth the price?
• Memory cards: Specifications and (more) deceptions
• USB activation dongles: Counterfeit woes
• Apple’s latest product launch event takes flight
• Apple’s fall 2024 announcements: SoC and memory upgrade abundance

The post Fooled by fake Apple AirPods 2: Fool me once, shame on you appeared first on EDN.

Infineon Technologies AG is launching the XENSIV TLE4802SC16-S0000, an inductive sensor designed to enhance performance in automotive chassis applications. The sensor enables high-precision torque and angle measurements with robust stray field robustness, supporting digital output via SENT or SPC protocols. It achieves highly accurate sensing without needing additional shielding. Tailored for use in electric power steering systems, including torque and steering angle sensors, as well as pedal and suspension applications, the sensor offers both flexibility and reliability.

The XENSIV TLE4802SC16-S0000 combines a coil system driver, signal conditioning circuits, and a digital signal processor (DSP) in a single package. The sensor includes overvoltage and reverse polarity protection and comes in a RoHS-compliant and halogen-free surface-mounted TSSOP-16 package. It is qualified to AECQ100, Grade 0, for operation across a wide temperature range from -40°C to 150°C. Furthermore, the sensor is fully compliant with ISO 26262, making it ideal for safety-critical systems. A built-in cybersecurity function protects the system communications against man-in-the-middle attacks. The TLE4802SC16-S0000 is the first in a new family of inductive sensors, with further variants planned for release.

The post Infineon introduces XENSIV TLE4802SC16-S0000 with inductive sensing for higher accuracy and performance appeared first on ELE Times.

I found some jokes when disassembling my old chromebook. submitted by /u/Vollgrav [link] [comments]

Відновлювана енергетика та енергоефективність у XXI столітті. Виклики та майбутнє kpi вт, 06/10/2025 - 10:21

submitted by /u/OpheliasStudio [link] [comments]

i recently opened up my Viofo A229 Pro to replace the thermal paste. On the left you can see the super-capacitor. Maybe someone finds it interesting like me submitted by /u/SchlumpfLP007 [link] [comments]

3D-printed SnapFit Modular Frame (Proof of Concept) For people who work with breakout modules, we are using breadboard for so long! Breadboard is great for building some circuit to test, but for breakout modules? it just a holder it limited choice and power supply rail for dupont wires. I propose alternative way to construct prototype circuit from breakout modules, since is fast, cheap and more flexible, suitable for exploring new modules and prototyping, compare to designing our own PCB or Soldering Purfboard. This is a work in progress, currently at the proof-of-concept stage and I would like to discuss about usabillity of this concept. The design is based on two key principles: Firmly holds components together No screws required Inspired by DIN rails, this system enables fast assembly and high flexibility for modular electronics setups. 🔗 View on Thingiverse All current designs are available on Thingiverse. Feel free to explore and discuss if you'd like to design your own holder for additional module submitted by /u/menginventor [link] [comments]

Зустріч між новим головою Наглядової Ради і керівництвом КПІ ім. Ігоря Сікорського kpi пн, 06/09/2025 - 19:09

Editor’s Note: This DI is a two-part series.

In Part 1, Nick Cornford deliberately oscillates the TDA7052A audio power amplifier to produce a siren-like sound and, given the device’s distortion characteristics, a functional Wien bridge oscillator.

In Part 2, Cornford minimizes this distortion and adds amplitude control to the circuit.

In the first part of this Design Idea (DI), we saw how to use the TDA7052A (or similar) power amp to build a minimalist siren-type power oscillator, and also, having looked at that device’s distortion characteristics under various operating conditions, a simple but half-decent Wien bridge oscillator. In this second part, we’ll turn that semi-decency into something even more respectable, concentrating on minimizing distortion and ignoring the siren song of raw power. We will also stick with a 5-V supply, even though the chip can handle up to 18 V. Figure 1 shows the new circuit.

Figure 1 Adding more precise level-sensing allows much better amplitude control and also reduces distortion.

Most of the changes are in the control loop, but input resistor R5 has been increased because we have more gain available now that Vcon can be driven high as well as just being pulled low. In passing, the series combination of R5 and U1’s nominally 20k input resistance shunts R2/R4 a little; a slightly disturbing operation. Adding 120k across R1/R3 could compensate for that, but the practical difference is tiny. The gangs on twin pots never quite match anyway, so using the lower-value half for R1 is good enough.

Wow the engineering world with your unique design: Design Ideas Submission Guide

The control loop, detailed

Peak output levels are now sensed by comparison with the reference voltage defined by R9 (or its wiper) and R10. (Be careful: pot R9 and fixed resistor R10 should match, so the latter may need to be trimmed.) The junction of R11 and R12 floats at ~650 mV until the peak amplitude exceeds the reference, when D1 or D2 will briefly pull it lower by ~450 mV. The resulting attenuated pulse stream is filtered by R6/C6 and R7/C7 and level-shifted and buffered by Q1 into U1’s Vcon pin. That attenuation is necessary because the effective control-loop gain would otherwise be excessive. U2 is an MCP6022, which has a low input-offset voltage and is fast enough to work well as a comparator. The overall temperature stability is good, the output level scarcely changing between 20°C and ~50°C.

Any residual ripple in a control loop like this will cause distortion by modulating the signal. It’s minimized by the lead-lag filter R6/C6 and C7/R7, which also controls the settling time. The values used leave the loop somewhat under-damped at low frequencies, but are a good compromise.

The spectra with unloaded outputs at 0 dBV and -10 dBV are both shown in Figure 2.

Figure 2 The spectra for 1 kHz outputs at 0 dBV and -10 dBV, showing THDs of around -60 and -73 dB respectively—say 0.1% and 0.02%.

Further reducing the output levels doesn’t improve distortion much, partly because this control scheme then becomes less stable. Any offset of one output relative to the other can result in one “phase” of pulses being missed, leading to increased second-harmonic distortion, as implied by the relative levels of second and third harmonics for the two levels shown in Figure 2. Trimming the power amp’s offset makes surprisingly little difference, so it isn’t implemented.

Trying to derive the control voltage from a more complex full-wave rectifier gave virtually the same distortion figures, so we’ll stick to Figure 1’s circuit, run it at -10 dBV or a little less, and accept its THD.

 Some finishing touches

Swapping the capacitors C1 and C2 for 3n3 and 330n parts gave the expected performance on higher and lower ranges, though distortion was a few dB higher on the low range, and the level was less well-controlled at the highest frequencies. All that’s needed to turn this into a useful kit is an output stage, for which the fairly conventional circuit of Figure 3 works well.

Figure 3 A simple output stage can deliver up to about +5 dBV, which is the rail-to-rail swing for a 5 V supply.

The extra stage adds almost no distortion, and leaves a spare op-amp (U3b) which could be used to invert the signal from U3a to provide antiphase outputs. One final spectrum, taken with the oscillator set for -10 dBV and the output for a swing of nearly 5 V, is in Figure 4. That confirms an overall THD of -73 dB, or 0.022%. Hardly earth-shattering, but still quite decent.

Figure 4 The spectrum at the output of Figure 3 for an output of ~+5 dBV.

No tweeters were harmed in the making of this DI, though a 10-Ω, 1/4-W load resistor started to smoke. A 1-W part would have been healthier, as it would only have vaped.

—Nick Cornford built his first crystal set at 10, and since then has designed professional audio equipment, many datacomm products, and technical security kit. He has at last retired. Mostly. Sort of.

Related Content

• Power amplifiers that oscillate—deliberately. Part 1: A simple start.
• Ultra-low distortion oscillator, part 1: how not to do it.
• Ultra-low distortion oscillator, part 2: the real deal
• Distortion in power amplifiers, Part IV: the power amplifier stages
• A pitch-linear VCO, part 1: Getting it going
• A pitch-linear VCO, part 2: taking it further

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Qualcomm’s $2.4 billion acquisition of Alphawave Semi is expected to take the San Diego, California-based semiconductor powerhouse beyond mobile processors and into the world of AI and data center chips. Here is a closer look at how Alphawave’s SerDes and chiplet technologies could aid Qualcomm in making a foray into the booming markets for AI and data centers.

Read the full story at EDN’s sister publication, EE Times.

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