Microelectronics world news

Teledyne e2v HiRel Electronics of Milpitas, CA, USA (part of the Teledyne Defense Electronics Group that provides solutions, sub-systems and components to the space, transportation, defense and industrial markets) has partnered with distributor Flip Electronics of Alpharetta, Georgia, which will maintain inventories of its wafers for military applications, ensuring a consistent and reliable supply of critical components...

The highly anticipated Bluetooth 6.0 specification is here, and one of its most notable features is the addition of channel sounding, a two-way ranging technique between two Bluetooth Low Energy (LE) devices. While Bluetooth LE is known for its low power consumption and cost effectiveness, it isn’t an optimum solution for reliable and accurate ranging.

Bluetooth Channel Sounding addresses these shortcomings by improving reliability and accuracy with distance measurement capabilities. That will significantly enhance high-volume applications such as personal item tags and key fobs, where presence detection and proximity sensing are crucial. Channel Sounding can be integrated into Bluetooth devices using a single antenna without requiring significant hardware modifications.

What’s Bluetooth Channel Sounding

Bluetooth Channel Sounding—a new protocol stack designed to enable secure and precise distance measurement between two Bluetooth LE-connected devices—unlocks a world of possibilities for embedded developers. It enables Bluetooth received signal strength indicator (RSSI) to open the door for a new wave of applications in localization and proximity awareness.

Localization applications like pet and asset trackers utilize locator devices to find the exact position of a tracking device. Next, proximity awareness applications such as smart locks and keyless entry systems utilize enhanced security features to restrict and control access to secure spaces and systems.

Figure 1 Bluetooth Channel Sounding improves accuracy to the sub-meter level and can be used in consumer, commercial and industrial applications. Source: Silicon Labs

So far, Bluetooth RSSI has relied on estimations to determine location, which leads to issues like multipath and obstruction. That, in turn, significantly reduces accuracy. Bluetooth Channel Sounding addresses this by improving accuracy to the sub-meter level. “The Bluetooth SIG’s adoption of Channel Sounding significantly enhances the precision of previous Bluetooth distance measuring techniques and encourages innovation across the Bluetooth device ecosystem.,” said Øyvind Strøm, EVP of BU Short Range at Nordic Semiconductor.

Security is of utmost importance to ensure that no unauthorized user can access the network. Channel Sounding incorporates robust security features to protect against tampering and man-in-the-middle (MITM) attacks. That’s crucial in applications like smart door locks, home appliances, and Find My solutions. For instance, Channel Sounding ensures lock only opens when the authorized device is within a certain distance.

How it works

Bluetooth Channel Sounding uses two proven ranging methods—phase-based ranging (PBR) and round-trip time (RTT)—to deliver true distance awareness between Bluetooth-connected devices. The connected devices use PBR, RTT, or both to coordinate ranging data between up to 72 channels within the 2.4 GHz spectrum and use one to four antenna paths between the two connected devices.

PBR utilizes the difference between the phase of the transmitted and received signal to calculate the distance between the initiator and reflector devices. It compares the phase difference between these devices to accurately measure the distance between them. An initiator device sends a signal to a reflector device, which returns the signal, and this process is repeated across multiple frequencies.

Figure 2 PRB delivers precise distance measurements between two Bluetooth devices using the number of wave cycles needed for the signal to go from the transmitter to the receiver. Source: Bluetooth SIG

In RTT, the secondary ranging method, an initiator device sends cryptographically scrambled packets to a reflector device, which returns the packets. Next, the distance between the devices is calculated based on the time the packets traveled back and forth.

Figure 3 RTT uses time of flight (ToF) to estimate the distance between the initiator and the reflector and cross-check the PBR measurement. Source: Bluetooth SIG

RTT can be used to verify and cross-check the PBR measurements. This cross-verification process helps detect anomalies and ensure applications are secure. For instance, it serves as a countermeasure against sophisticated man-in-the-middle attacks.

True location awareness

Channel Sounding is expected to be widely adopted in mobile phones and a broad range of products such as Bluetooth mice, keyboards, and game controllers. Then there are Find My applications—Bluetooth tags attached to personal items such as keys, wallets, backpacks, and luggage—where developers can add true distance awareness to make it easier and quicker for users to locate lost items.

After Bluetooth SIG’s adoption of Channel Sounding as part of Bluetooth 6.0, Nordic Semiconductor has announced support for the technology in its forthcoming nRF54L and nRF54H Series RF chips. Silicon Labs has also announced the integration of this technology in its xG24 wireless chips and antenna hardware solutions.

Channel Sounding technology in Bluetooth 6.0 marks a significant step in the evolution of modern wireless, and its true wireless awareness is expected to unlock new use cases while optimizing existing ones. As Ross Sabolcik, senior VP of the Industrial and Commercial Business Unit at Silicon Labs, puts it, in a world where location awareness is critical, Channel Sounding revolutionizes proximity and location capabilities, propelling Bluetooth technology into a new era.

Related Content

• Bluetooth low energy (BLE) explained
• Inside Bluetooth low-energy technology
• The basics of Bluetooth Low Energy (BLE)
• Waking Up to Thrill of Bluetooth’s 3rd Innovation Wave
• Bluetooth Channel Sounding Improves Distance Estimation Accuracy

The post A short design tutorial on Bluetooth Channel Sounding appeared first on EDN.

The JEDEC Solid State Technology Association (which develops standards for the microelectronics industry) has published ‘JEP200: Test Methods for Switching Energy Loss Associated with Output Capacitance Hysteresis in Semiconductor Power Devices’. Developed jointly by the JC-70.1 Gallium Nitride and JC-70.2 Silicon Carbide Subcommittees of JEDEC’s JC-70 Wide Bandgap Power Conversion Semiconductor Committee (which was formed in October 2017 with 23 member companies, rising to over 80 now), JEP200 is available for free download from the JEDEC website...

This printer pissed me off. Screw him. I spent so much money on this thing. Print head. $250. Ink refilling kit and ink cartridges. $100. Twice. Ink, ink and more ink. This fucking thing takes 8 ink cartridges! Bought 13x19 large format ink jet photo paper…couldn’t use because the print head SUCKS! AGAIN! Bought another print head from Ali Express $160. It’s used and not new! And inconsistent print quality. So I did what every sane person would do. I took that thing and ripped it to shreds. I’m redacting the make and model of this fucking thing, because I don’t really want to shit on this brand. It’s a good brand; it’s just my situation that sucks. I’m part of the reason why this printer sucks, not the brand. Being cheap and all, buying print heads from Ali Express, ink and refillable cartridges from eBay. It’s because the ink cartridges are insanely expensive! I wasted an entire set of manufacturers ink cartridges (8 of these cunt cartridges!) from cleaning the fucking print head! That’s why I bought cheap refillable ink from eBay. Then the print heads decided to go on vacation, and now we’re here. So fuck it. I tore that shit apart, and from the magic of ESP32 modules, H-Bridge L298N motor controllers, and a little bit of code, I’m turning this thing into something even more useless and retarded. Because I’m mad. And, because I really hate throwing stupid shit like this in the trash. First order of the day. Taking that SMPS power supply that came with the thing and fucking it up. Cracked the case open, plugged it in, force enabled the output, and putting it on an electronic DC load and driving it hard. The output is rated for 32v 0.7A. Screw that. With the DC load, I squeezed out 32v at 5 amps. 125mv RMS ripple at full load is crap, but I don’t care. As long as I can overvolt its fucking motors with using the original power supply, I’m happy. Doing my best to not contribute to the earths eCycle waste issue by repurposing most components from this printer to make something even stupider and useless. Reduce, Reuse, and Recycle motherfucker. One good thing is that the thermal cutoff works; power supply took a shit at 80° C. I freeze sprayed that bitch until it turned back on. Then continued to make it draw 32v 5 amps. Thermal cutoff keeps tripping; that’s ok…I have lots of freeze spray to wake his ass up. I mean, I have to make sure the power supply that came with this thing can handle the currents I plan on delivering to the 4 DC motors in this thing. Stay tuned to what other ridiculous useless piece of shit machine I can turn this thing into. submitted by /u/Asuntofantunatu [link] [comments]

Overswing can occur when Zener diodes are pushed to their limits. Learn about why this happens and the problems it causes—and how to overcome the issue.

I recently added a 6 channel sequencer in a drawer under the rack to allow on-the-fly edits of all the drum parts in one place. The control module on the left has an arduino that handles all the preset patterns, functions, and the chain of shift-registers to keep track of all the buttons and LED’s. The sequencer uses a couple CD4017 counters and some diode logic to generate the control signals for the drums. The drum board is made up of several bridged T filters and some white noise that are combined and fed to an output mixer. The spaghetti inside is (hopefully) temporary until I can figure out a better system to wire everything together. submitted by /u/jellzey [link] [comments]

Infineon Technologies AG of Munich, Germany is one of three teams nominated by the jury for the Deutscher Zukunftspreis 2024, the German Federal President’s Award for Technology and Innovation (to be awarded by Federal President Frank-Walter Steinmeier in Berlin on 27 November)...

In this article, we'll learn how the transformer-coupled voltage-switching Class D amplifier works and highlight some of its advantages.

A few weeks back, in mid-August to be exact, I pointed out that Google had for the first time in my memory gotten the jump on Apple, pulling in its traditional October launch event by two months in order to launch its latest smartphones, smartwatch, and earbuds ahead of its key competitor. So, it was ironic that the very same day Apple announced its latest smartphones, smartwatch and earbuds, the reviews on Google’s Pixel Watch 3 went public, one day ahead of that device’s ship date. Touché, eh?

Smartwatches weren’t the only thing Apple unveiled today (as I write these words on Tuesday evening, September 9). In the paragraphs that follow, I’ll give commentary on each notable news item in chronologically-announced order, as well as mentioning what didn’t get first-time unveiled (or at least updated) today and therefore what might be coming in the (near?) future.

The Apple watch series 10 (and, ok, a new-color Watch Ultra 2)

Thinner. Lighter (due in part to a repackaged S10 SiP SoC, which I’m betting is otherwise identical to its S9 predecessor). A bigger, curved display with improved off-axis brightness. Only accompanied, unfortunately, by the same “all-day” (since when does a day have only 18 hours?) battery life claim as with prior-generation models. That’s the Apple Watch Series 10 in a nutshell. But what I’d like to spend a bit more time on is a first-time feature that Apple spent a fair bit of time on (and which is near and dear to my heart): sleep apnea detection.

Company officials (in their as-usual nowadays pre-recorded pitches) claimed that 80% of sleep apnea goes undetected, without referencing a specific source of this information. But its veracity wouldn’t at all surprise me. That Apple’s supporting this capability is therefore great. However, the method by which the company is claiming to detect breathing interruptions—movement—is admittedly more than a bit baffling to me.

SpO2 (oxygen saturation) sensors already in use in smartwatches as well as dedicated-function pulse oximeters would be a logical place to log such data for analysis; a fingertip sensor was in part how my own sleep apnea was initially confirmed via an at-home sleep study. But Apple remains mired in patent infringement litigation and counterclaim battles with Masimo, a pulse oximeter manufacturer. Another increasingly common approach, employed by devices such as Google’s second-generation Nest Hub (which I’ve personally test-driven) and Amazon’s Halo Rise, leverages anonymity-preserving millimeter wave radar to count the chest rise and fall cadence and any rhythm deviances…but from a device a foot (or few) away from you. How Apple’s discerning a breathing pattern from a device strapped to your wrist without using a Spo2 sensor is beyond me…unless Apple’s leveraging the integrated ultra wideband transceiver, akin to how Wi-Fi can be used to detect, count, and track the movements of people in a room? And speaking of sensors, Apple’s added water depth and temp sensing for swimmers, too.

And yes, the Apple Watch Ultra 2 now comes in a black patina, too. My wife still loves her first-generation Watch Ultra. And I still love that I got her a brand new-looking first-gen refurb, versus dropping notably more coin on a truly brand-new, marginally upgraded gen-two. ‘Nuff said.

Gen4 AirPods (and, ok, tweaked AirPods Pro and AirPods Max)

Here’s another example of the combo of notably advanced and more modestly evolved offerings, blurring product line distinctions in the process. Two years ago at this time, Apple had announced its third-generation entry-level AirPods, with only slight advancements over their precursors, along with more significant improvements to the second-generation AirPods Pro. Last year at this time, Apple migrated the AirPods Pro case from Lightning to USB-C (presumably to address European Union demands, among other factors). This year, the baseline AirPods got the notable-upgrade attention, migrating to the beefier-featured H2 SoC, moving from Lightning to USB-C too (although penny-pinching Apple dropped cables from the product packaging in the process), and including a more expensive active noise cancelation (ANC) product option.

That said, the overall noise cancellation capabilities of the AirPods Pro are probably still at least a bit better, due to their eartip-inclusive in-canal design (which some folks love, and others detest, versus the simpler in-ear approach). By the end of the year, Apple plans to add clinical-grade hearing aid support to the AirPods Pro 2, which is rumored to be gaining more meaningful third-gen upgrades such as heart rate measurement thereafter. And what about the over-ear AirPods Max? They’ve also migrated from Lightning to USB-C as of this week, along with gaining a refresh of the available color schemes but are otherwise identical to their precursors (which was a relief to this guy, who’d gotten a refurb “space gray” set for his birthday back in May). Funny how significant-discount sales can tip one off to a pending product line refresh (therefore an in-advance flush of existing-product inventory in retail channels), isn’t it?

The iPhone 16 family

It’s no secret at this point that, as this guy forecasted nearly a year ago, an increasing number (and percentage) of folks are holding onto their smartphones longer than they did before. Manufacturers’ responses to this trend are predictable: they specifically encourage folks who are upgrading in a given product cycle to pick higher-end, more expensive variants (“Pro” for both Apple and Google, for example), and in general they raise prices across the product line year-to-year. Note, for example, my commentary on Google’s last-month announcements. Or look at what Apple did a year ago at this time. Only the “Max” variants of the iPhone 15 got the newest A17 (Pro) SoC; standard iPhone 15s were stuck with the A16 Bionic from the previous year’s iPhone 14 Pro. That processing differentiation, along with a larger RAM allocation on Pros, meant that they’re the only iPhone 15s capable of running upcoming Apple Intelligence (the company’s branded, preferred spell-out of the AI acronym) capabilities.

Speaking of Apple Intelligence, its resource needs have apparently driven a strategy deviance-from-recent-norm for at least this year. Both the conventional and “Pro” variants of the new iPhone 16 come with the latest A18 SoCs, and the chip versions are seemingly quite similar (although Apple never reveals clock speeds, for example); both included six CPU cores (two performance, four efficiency) and the GPU architectures deviate only in core counts (5 for the baseline A18, 6 for the “Pro”, presumably to maximize overall manufacturing yield). That said, Apple claims that as with past generational steps, it’s made iterative optimizations to the 16-core Neural Engine on-chip deep learning inference coprocessor in both SoCs.

Speaking of manufacturing, both A18 variants are fabricated on the same second-generation 3 nm TSMC process that also acts as the foundry source for the M4 SoC announced earlier this year and to date found only in the iPad Pro. As with past development-sharing examples, I’m guessing that there’s a fair bit of architectural commonality between the M4 and A18. Here’s a summary of Apple’s claimed performance improvements for its two A18 variants:

• A18: 30% faster CPU, 40% faster GPU, 17% higher memory bandwidth than A16 Bionic
• A18 Pro: 15% faster CPU, 20% faster GPU, 17% higher memory bandwidth than A17 Pro

Integrated RAM deviances (or not) between standard and “Pro” A18 SoCs (therefore phones based on them) are unknown at this point. And by the way, the non-“Pro” version of the A17 SoC is still MIA. Furthermore, with the iPhone 15 Pro phones (along with the iPhone 13 line) obsoleted as of this week, the broader A17 SoC line may now be deceased.

Both the standard and “Pro” versions of the iPhone 16 add a dedicated function (albeit multi-function) “camera control” button, in addition to carrying forward the “action” button that had replaced the “mute” switch on the iPhone 15 Pro models. Unsurprisingly, “Pro” iPhone 16s also offer enhanced front- and rear-camera allocations as compared to their conventional siblings:

• Rear:
  • 48 Mpixel main with 24 mm focal length and ƒ/1.78 aperture
  • 48MP ultrawide with 13 mm focal length and ƒ/2.2
  • 12 MPixel 5x telephoto with 20 mm focal length and ƒ/2.8 aperture (in contrast, the 5x support was only offered in last year’s iPhone 15 Pro Max variant)
• Front: 12 Mpixel with ƒ/1.9 aperture

Unlike in the past, the Pro and Pro Max have identical camera setups. Speaking of cameras, they now capture 4K 120 fps video, along with spatial audio (the latter courtesy of an integrated four-microphone array). Also unlike in the past, they’re both larger in display sizes than their non-Pro counterparts:

• iPhone 16: 6.1” diagonal
• iPhone 16 Max: 6.7” diagonal
• iPhone 16 Pro: 6.3” diagonal
• iPhone 16 Pro Max: 6.9” diagonal

No-shows = Next announcements?

Those are the highlights, IMHO. For more, check out the coverage elsewhere, including archived liveblogs. But what didn’t arrive this week, some of which had been rumored beforehand? Well, there’s…

• A true next-gen Watch Ultra (3)
• A next-gen Watch SE (a plastic version had specifically been prognosticated)
• The aforementioned AirPods Pro 3
• Any new iPads (the existing iPad mini 6, which I own is getting particularly “long in the tooth”)
• A new iPhone SE, or
• Any M4-based Macs, following up on the M4-based iPad Pro from earlier this year

My guess would be that, particularly focusing on that last bullet point, we’ll see at least one more round of announcements before the end of the year. Whether they’ll be press-release-only or clusters in an event (next month, mebbe?) is anyone’s guess at this point. But regardless, you know where you’ll find coverage of them. See you then!

—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

• Google’s fall…err…summer launch: One-upping Apple with a sizeable product tranche
• The 2024 WWDC: AI stands for Apple Intelligence, you see…
• Apple’s Spring 2024: In-person announcements no more?
• Apple’s latest product launch event takes flight
• Apple’s 2022 WWDC: Generational evolution and dramatic obsolescence

The post It’s September in Apple land, so guess what it’s time for? appeared first on EDN.

Psychologists tell us that frustration increases drive. I was driven to produce the circuit in this design idea by my increasing frustration with a collection of digital thermometers, all of which claimed accuracy to within 0.1°C but the readings of which were mismatched by anything up to a couple of degrees, showing a serious lack of precision.

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

Such thermometers generally use thermistor sensors, which have a roughly exponential relationship between temperature and resistance. That is tricky to convert into a usable signal with good linearity over a wide measurement range. Alternatives are thermocouples, with their low voltage outputs, and resistance temperature detectors (RTDs), which use the temperature coefficients of metals, usually platinum, to give decent outputs which are linear with respect to temperature over a wide range.

The final impetus for this project came from the discovery of some long-mislaid PT100 RTD sensors, which enabled something fairly precise: a box to convert the RTD’s resistance into a millivolt signal which could be read directly on a standard digital multimeter (DMM). As usual, I have tried to push a simple design to its limits and to wring every last ounce (or milli-Kelvin) of performance from it.

RTD basic circuit

RTDs are generally used in bridge circuits as shown in Figure 1.

Figure 1 A bridge incorporating an RTD produces a voltage output related to the temperature, but usually with an offset 0°C point.

R1 and R2 feed current through the RTD and R3, whose resistance is around the mean value of the RTD’s. The voltage across the bridge is then nearly proportional to the temperature, but with an offset. Note that weasel word “nearly”! For an exactly linear relationship between sensor resistance and temperature, R1 and R2 would need to be infinite, implying an unhelpfully infinite drive voltage—or they could be replaced with matched current sources, as in Figure 2.

Figure 2 Using matched current sources in the bridge gives a linear relationship between temperature and output, and helps us define a reference point of 0 °C. Choosing the currents carefully gives a bridge output of 1 mV / °C.

PT100 RTDs, which use (precisely doped) platinum wire or film, are defined to have resistances of 100 Ω at 0°C and 138.5 Ω at 100°C. Using identical currents in each leg of the bridge means that if the reference resistor R3 is 100 Ω, the bridge will be perfectly balanced at 0°C, with zero voltage between the output terminals. If the currents in each leg are set to (∆T°/∆R), or (100/38.5) = 2.597…mA, the differential output voltage will change by exactly 1 mV/°C. Measuring that output with a DMM on its millivolt range will then show the temperature directly.

Practical RTD circuit

Figure 3 shows how to do this for real.

Figure 3 A practical circuit capable of delivering exactly 1 mV/°C.

A1-A/Q1/R5 and A1-B/Q2/R6 form the pair of constant-current sources—or rather sinks, since we have turned the circuit upside down. The common reference for each comes from D2, a precision 1.24-V reference, potted down to about 1.12 V, which is of course the (theoretical) voltage that 2.597…mA produces across 430 Ω. The differential voltage across the outputs is now just what we want: 0 V at 0°C and 100 mV at 100°C. (In a perfectly-designed world, where TCRs stayed constant from absolute zero to 2044 K—the melting point of platinum—we’d be using a current of 2.7315 mA.)

The other odds and ends to the left of the schematic are boring practicalities: a CR2032 3-V coin cell, a push-to-read switch, as well as a series diode and resistor feeding a white LED which just dims out at the minimum usable battery voltage of about 2.7 V, where the second decimal place starts to wander. (That power/low battery indication is adequate for lab use, if rather basic.) Consumption measured around 8 mA.

Calibration is necessary but easy. To set the 0°C point, immerse the RTD in crushed, melting ice and adjust R8 for zero output voltage. Then hang it in the steam above the water in a kettle just off the boil and trim R5 for an output of 100.0 mV. That’s it!

Considering error

It works. It’s simple. It’s correctly set up. What could possibly go wrong?

Firstly, there are the connections to the RTD, with their own resistances adding to that of the sensor. This unit only needed a meter or so of cable as it was purely for lab use. The length of 18 AWG (~1 mm2) wire has a loop resistance of ~90 mΩ, giving an error of ~0.02°C: ignorable, as is the second-order effect of the temperature coefficient of resistance (TCR) of the copper leads themselves. However, many RTD assemblies (as opposed to basic sensor elements) come with three wires, allowing a configuration where this error completely cancels out, assuming that all wires have the same resistance, as shown in Figure 4.

Figure 4 Three-wire connection to the RTD allows cancellation of the cable’s resistance.

Secondly, there is self-heating of the sensor. Most RTD circuits use a 1-mA sensing current, but our ~2.6 mA will dissipate more, around 1 mW. Basic RTD elements are quoted as having thermal resistances of about 20°C/W, so the error may be +~0.02°C, depending on the medium in which the device is immersed and whether that is still or moving. In still air, it could read at least 0.1°C higher than in flowing water. If you are going to use it in air, it’s probably best to set the zero point with the RTD in a cavity surrounded by ice and water rather than immersed in those.

Next, there will be offsets and mismatches in the circuit, which will balance as long as the two current sinks have the same errors, which can be calibrated out. Q1 and Q2 should be matched for hFE because their base currents produce slight excess voltages across R5 and R6, and those need to match for the best temperature stability. (This is really finicky. The sensor may be swinging wildly in temperature, but the measuring circuitry should not be. And the LM385-1.2 reference has a very low voltage tempco in the room-temperature region.)

Using MOSFETS for Q1/2 would have been preferable, their gate currents being zero(ish), but the 3‑V supply did not allow that, at least with the devices on hand. The finite but high values for the sinks’ compliances can be ignored.

Other errors in the 0° and 100° calibration points are possible. The ice for your calibration bath should ideally be made from distilled or at least de-ionized water. (For the curious differences between waters, see this article, and then ignore its implications for this device.)

Boiling point is trickier. At sea level with the atmospheric pressure at 1 bar, its precise value is defined as 99.97°C. The drop in pressure with height reduces water’s boiling point by about 1° for every 300 m increase. Check your altimeter and barometer and adjust accordingly. This is a useful tool for doing so.

Lastly, there is the DMM with which this will be used. The 10-MΩ input resistance of most meters will introduce only a tiny error, which will be compensated for during calibration. Use the highest-resolution meter you must set zero degrees but your target meter for the 100°C point to avoid any meter-calibration issues. Even the cheapest meters (sub-$/£/€5) usually have a 199.9 mV range; why not get one and keep it for thermometry?

Despite all the above fussing and dooming and glooming, only a little care is needed to achieve 0.1°C precision, which is much better than most thermistor-based thermometers can offer. For greater resolution, with another (accurate but imprecise) decimal place, use a 4½-digit meter for the readout. Professional metrologists may quibble over some of the details, but I hope not too violently.

Those MOSFETS for Q1/2 that we met earlier but rejected: with a higher supply voltage and a different op-amp, they can still be used. A TLV2372 (RRIO) would be ideal, but an LM358 works well, as it can sense down to ground and (just) drive up to the positive rail, with input offset currents which are adequately low and fairly constant. In the test, using ZVN3306A MOSFETs, that variant gave stable results with a supply ranging from 4.6 to 30 V. (R2 was increased for the higher voltages.)

Unequal bridge currents

So far, the currents in the two legs of the bridge have been equal, but they need not be, as the reference current defining the 0°C point can be much lower. Increasing R6/7/8 by ten times or so saves a couple of milliamps with no practical downsides that I can spot, especially when using the MOSFETs. The leads to the sensor must then be short, because the lead resistance compensation scheme shown in Figure 4 only works with equal currents. My Mark 2 version, shown in Figure 5, uses this 10:1 current ratio along with other changes to suit the 9-V supply. It too works fine, drawing about 6 mA.

Figure 5 A higher battery voltage allows the use of MOSFETs in the current sinks, while a lower current in the reference arm of the bridge saves some supply current.

It should be possible to feed the differential output through an instrumentation amp (with gain) to an ADC. Note the phrasing, which means I have neither tried nor even considered that approach in detail. This device was developed for lab use, not a process-control environment.

For a true, full-DIY version, around 100 Ω-worth of (very) fine copper wire should make a good sensor, if you have some patience. Copper’s TCR is close to that of doped platinum (Cu: 3.93 ppt/K; Pt: 3.85) so only alterations to R7/8 (to match the actual resistance) and slight re-trimming of R3 (for the copper’s TCR) would be needed. The 100-Ω RTD figure is common but not mandatory. For higher sensor resistances, use lower drive currents (giving less self-heating), adjusting R5 (and perhaps R6/7/8) to suit.

Perhaps the coil from that junk-boxed analog meter may yet come in handy?

—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

• Minimize measurement errors in RTD circuits
• Designing with temperature sensors, part three: RTDs
• RTDs provide differential temperature measurement
• Current source allows measuring three-wire RTD
• ADC Requirements for RTD Temperature Measurement Systems
• Ultra-low distortion oscillator, part 1: how not to do it.

The post DIY RTD for a DMM appeared first on EDN.

Infineon Technologies AG of Munich, Germany has developed what it says is the first 300mm power gallium nitride (GaN) wafer technology to be applied in an existing and scalable high-volume manufacturing environment, helping to drive the market for GaN-based power semiconductors. Compared with 200mm-diameter wafers, 300mm wafers allow the production of 2.3 times more chips per wafer...

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

Independent power electronics company Quantum Power Transformation (QPT) Ltd of Cambridge, UK — which was founded in 2019 and develops gallium nitride (GaN)-based motor drives — has appointed Dr Simon Hart as an advisor to its board. He is an Honorary Associate Professor and Entrepreneur-in-Residence at the University of Nottingham, and holds C-level roles at several technology companies...

At European Microwave Week (EuMW 2024) in Paris, France (24–26 September), Altum RF of Eindhoven, The Netherlands (which designs RF, microwave and millimeter-wave semiconductors for commercial and industrial applications) is showcasing its featured products and technical expertise in booth #815B at Paris Expo Porte de Versailles...

A European research and industry consortium led by engineered substrate manufacturer Soitec of Bernin, near Grenoble, France has begun work to develop a future generation of high-frequency semiconductors based on indium phosphide (InP)...

Specialty analog foundry Tower Semiconductor Ltd of Migdal Haemek, Israel has announced the production of Wi-Fi 7 RF front-end module (FEM) devices based on its 300mm radio frequency silicon-on-insulator (RFSOI) technology. Partnering with Broadcom Inc, Tower has enabled fully integrated Wi-Fi FEM devices on a single RFSOI die. The solution delivers superior performance and efficiency compared with existing non-SOI technologies...

The 14-bit scope combines architectural improvements and software support for higher resolution, real-time processing, and enhanced signal analysis.

GlobalFoundries (GF) of Malta, NY, USA has joined the semiconductor startup ecosystem of Silicon Valley-based Silicon Catalyst (the only incubator+accelerator focused exclusively on semiconductor solutions) as a Strategic Partner and an In-Kind Partner (IKP). The partnership will provide innovative start-ups with access to GF’s differentiated platforms to speed the development and commercialization of next-generation IoT, automotive and generative AI applications while anticipating future growth markets such as medical and quantum compute...

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