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A closer look at PCIe 6.0 interoperability, performance testing

PCIe, the most successful interconnect technology for more than 25 years, is entering a new phase of complexity with the adoption of PCIe 6.0, which is now largely driving artificial intelligence (AI) workloads. Gary Hilson talks to senior managers at Broadcom and Astera Labs to understand issues related to PCIe 6.0 system design, interoperability and performance testing. These issues are critical in PCIe 6.0 deployment in advanced AI data centers.
Read the full story at EDN’s sister publication, EE Times.
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The post A closer look at PCIe 6.0 interoperability, performance testing appeared first on EDN.
Skorpios names Gunter Reiss as chief revenue officer
PWM-programmed LM317 constant current source

LM317 fans will recognize Figure 1 as the traditional LM317 constant current source topology. It closely regulates Iout = Vadj/Rs by forcing the OUTPUT pin to be Vadj = 1.25 V positive relative to the ADJ pin. Thus, Iout = Vadj/Rs to a very good approximation. Master chip chef Bob Pease cooked it up to be so!
Figure 1 Classic LM317 constant current source,
Iout = Vadj/Rs + Iadj ≃ Vadj/Rs = 1.25/Rs.
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In usual practice, Iout >> Iadj, the latter being specified at 50 µA typical, 100 µA max. This simplifies the math by making the Iadj bias current safely ignorable without letting accuracy take a hit. It’s worked great for 50 years but it has an obvious downside. the way you program Iout is by changing Rs.
Figure 2 shows a new(er) topology with a different (more agile) method for making Iout programmable.
Figure 2 A novel LM317 topology enables control of amps of Iout with just milliamps of Ic,
Iout = (Vadj – (Ic – Iadj)Rc)/Rs – Ic + Iadj ≃ (Vadj – (Ic – Iadj)Rc)/Rs.
Typically, Rc > 100Rs, making Figure 2 able to control up to 1.5 A of Iout with just milliamps of Ic. Of course, now it may no longer be good enough to just ignore Iadj.
Figure 3 shows the idea fleshed out into a complete PWM controlled 15 V, 1 A, grounded-load current source that includes Iadj compensation. Here’s how it works.
Figure 3 The 1-A, 15-V, PWM-programmed grounded-load current source with a novel LM317 topology. The asterisked resistors are 1% or better and Rs = 1.25 Ω.
The 5-Vpp PWM input has a frequency (Fpwm) assumed to be 10 kHz or thereabouts. If it doesn’t, scale C1 appropriately with:
C1 = 22µF*10kHz/Fpwm
The resulting PWM switching of Q2 creates a variable resistance averaged by C1 to Rc(1 + 1/Df) where Df = the 0 to 1 PWM duty factor. Thus a (0 to 2.5v)/2Rc = 3.11 mA Ic current = 2.5v/Rc(1 + 1/Df) flows into Z1’s summing point.
Z1 servos the V1 gate drive of Q1 to hold its source at an accurate 2.5-V reference for the PWM conversion and to level shift Ic to track U1’s ADJ pin. Also summed with Ic is Iadj bias compensation (2.5v/51k = 50µA) provided by R1.
The unsightly stack of six 1N4001’s is needed to provide bias for Q1 to work into. I freely admit that it’s not very pretty. Hopefully the novelty of Figure 2 makes up for it!
Note that accuracy and linearity mostly depend only on the match of the Rc resistors and the precision of the Z1 and U1 internal references. It’s a happy coincidence that the 2:1 ratio of the TL431’s 2.5-V versus the LM317’s 1.25 V permits the convenient use of three identical Rc resistors.
If Rs = 1.25 Ω, then Iout(max) = 1 A and Iout versus Df is as plotted in Figure 4.
Figure 4 Iout versus Df where Df (x-axis) is the PWM duty factor and Iout (y-axis) is Vadj/1.25 = 1 A full-scale = 1 – 2/(1 + 1/Df).
Df versus Iout is plotted in Figure 5.
Figure 5 Df versus Iout where Iout (x-axis) is 1 A full-scale and Df (y-axis) = 1/(2/(1 – Iout) – 1).
Note that U1 might be called upon to dissipate as much as:
- 20 W if Rs = 1.25 Ω and Iout(max) = 1 A
- 30 W if Rs = 0.83 Ω and Iout(max) = 1.5A
Moral of the story: don’t be skimpy on the heatsink! Also note that Rs should be rated for a wattage of at least 1.252/Rs.
Then there’s the consideration of power up/down transients. When the system is first switched on and C1 is sitting discharged, and the controller will have about 4 to 8 milliseconds to initialize the PWM logic to 1.0 before C1 can charge enough to allow U1 to come on and start sourcing current. Don’t forget this detail during software development! On power-down, Q3 kicks in when +5 V drops below ~2 V. This saturates Q1 and forces Iout to zero to protect the load as well as discharging C1 in preparation for the next power-up.
In closing, thanks go (again) to savvy reader Ashutosh for his suggestion that the Figure 2 topology might deserve a focused DI of its own, and (likewise again) to editor Aalyia for the fertile DI environment she has created that makes this kind of teamwork, well, workable!
Stephen Woodward’s relationship with EDN’s DI column goes back quite a long way. Over 100 submissions have been accepted since his first contribution back in 1974.
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- Power Zener using the LM317
- Use an LM317 as 0 to 3V adjustable regulator
The post PWM-programmed LM317 constant current source appeared first on EDN.
USB-to-BLE bridge
![]() | Firmware is open source though. A small (52x30) PCB to forward USB HID reports over BLE. Plus additional buttons and a rotary encoder. [link] [comments] |
Transparent PCBs are so cool!
![]() | submitted by /u/1Davide [link] [comments] |
X-FAB, SMART Photonics and Epiphany Design demo InP-on-Si design flow for next-gen optical transceivers at OFC
Understanding Gold Soldering: Definition, Process, Working, Uses & Advantages
Gold soldering is a sophisticated metallurgical joining technique that represents the pinnacle of precision manufacturing processes. Unlike conventional soldering methods, this specialized technique involves creating permanent, high-integrity connections between gold or gold-alloy components with exceptional precision and reliability. The process goes beyond simple mechanical joining, instead creating a deep metallurgical bond that ensures optimal electrical, thermal, and structural performance.
How Gold Soldering WorksThe scientific principles underlying gold soldering are complex and multifaceted. At its core, the process involves creating an atomic-level bond between gold surfaces using a carefully selected filler material with a strategically lower melting point. The metallurgical interaction is not merely a surface-level connection but a profound interdiffusion of metal atoms that creates a seamless, integrated joint.
The fundamental mechanism begins with the careful preparation of surfaces, where even microscopic contaminants can compromise the entire soldering process. As the filler material is heated, it transitions from a solid to a liquid state, simultaneously wetting the gold surfaces and creating a capillary action that draws the molten material between the components. During this process, atomic diffusion occurs, where the atoms of the filler material intermingle with the gold surfaces, creating a bond that is often stronger and more reliable than the original base materials.
Gold Soldering ProcessSurface Preparation: The Critical First Step
Surface preparation is arguably the most crucial phase of gold soldering. This stage requires meticulous attention to detail and advanced cleaning techniques. Professionals employ a combination of chemical and mechanical methods to eliminate any potential contaminants. Specialized solvents are used to remove organic residues, while precise chemical etching or plasma cleaning techniques eliminate oxide layers and microscopic impurities.
The goal is to create an absolutely pristine surface that allows for maximum metallurgical interaction. Even a thin layer of oxidation or a microscopic particle can prevent proper bonding, leading to weak joints or complete soldering failure. Advanced cleaning techniques may include ultrasonic cleaning, chemical degreasing, and high-precision surface treatments that can remove contaminants at the atomic level.
Material Selection: A Delicate Science
Selecting the appropriate materials is a complex process that requires deep understanding of metallurgical properties. The gold alloy composition must be carefully matched with an appropriate filler material that can create a reliable bond while maintaining the desired mechanical and electrical properties. Factors such as melting point, thermal expansion coefficient, and chemical compatibility are meticulously evaluated.
Different applications demand different material characteristics. For instance, electronics may require a filler material that provides optimal electrical conductivity, while medical devices might prioritize biocompatibility and corrosion resistance. This selection process often involves extensive material testing and simulation to ensure optimal performance under various operational conditions.
Uses & ApplicationsElectronics Industry: Pushing Technological Boundaries
In the electronics industry, gold soldering is nothing short of revolutionary. Semiconductor packaging relies on this technique to create microscopic connections that form the backbone of advanced electronic devices. Hybrid microelectronics, which combine different types of electronic components, depend entirely on the precision and reliability of gold soldering techniques.
Modern smartphones, advanced medical imaging equipment, and cutting-edge aerospace technologies all benefit from gold soldering’s ability to create miniaturized, high-performance connections. The technique allows for the integration of components at nanoscale levels, enabling technological advancements that were previously impossible.
Medical and Aerospace Applications: Reliability in Extreme Conditions
In medical and aerospace domains, gold soldering’s reliability becomes paramount. Implantable medical devices require connections that can withstand the human body’s complex chemical environment, while aerospace components must endure extreme temperature variations and intense radiation.
The ability to create stable, corrosion-resistant joints makes gold soldering indispensable in these critical fields. Precision surgical instruments, satellite communication systems, and advanced sensor technologies all rely on the unique properties that gold soldering provides.
Advantages and ChallengesGold soldering offers remarkable advantages, including exceptional conductivity, corrosion resistance, and the ability to create extremely precise connections. However, these benefits come with significant challenges. The process is inherently expensive, requiring specialized equipment and highly trained professionals.
The narrow temperature window for optimal soldering demands extraordinary skill and precision. A deviation of mere degrees can compromise the entire soldering process, making it a technique that requires continuous training and technological investment.
ConclusionGold soldering represents more than just a joining technique—it is a sophisticated technology that pushes the boundaries of what is possible in manufacturing. As technological demands become increasingly complex, the importance of this precise metallurgical process will only continue to grow.
Professionals in electronics, medical technology, aerospace, and advanced manufacturing must continually invest in understanding and mastering these intricate soldering techniques to drive technological innovation forward.
The post Understanding Gold Soldering: Definition, Process, Working, Uses & Advantages appeared first on ELE Times.
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AI generated schematics Coming Soon™
![]() | submitted by /u/ryleymcc [link] [comments] |
TTL Nixie clock
![]() | Fully TTL driven Nixie clock I have been buildng recently. It have 6x IN-14 and 2x IN-19V Nixie tubes. Clock pulse is taken from mains frequency by optocoupler and devided by 7490 cunters. It can be set for 50Hz o 60Hz. There will be an option to choose beside Mains CLK, Crystal CLK and External CLK. There is also output to drive other clocks as "slave". Later on I will add "Day of the week" display. [link] [comments] |
Diodes Inc launches InSb Hall-element sensors for rotation and current detection applications
Scintil demonstrating LEAF Light DWDM remote light source at OFC
Optical PHYs facilitate 200G/lane speeds for AI clusters

Semiconductor compute has grown drastically over the past 18 to 24 months amid the vast artificial intelligence (AI) infrastructure buildup. Nvidia and hyperscalers have made many announcements about migrating to GPUs with 200 Gbps per lane speeds. However, with computation moving to higher data rates, optical connectivity must also migrate to higher data rates.
But here comes the rub. While the rapid growth of AI workloads drives demand for increased bandwidth and interconnect density in AI clusters, optical interconnect power is a major factor limiting cluster scalability. Broadcom claims its new Sian3 and Sian2M PHY chips supporting 200 G/lane speeds offer greater levels of power efficiency and cost optimization for next-generation AI infrastructure.
Figure 1 Sian3 and Sian2M DSP PHYs enable module developers to rapidly address the growing demand for 200G optics in AI. Source: Broadcom
Optical connections can be short-reach or long-reach because sometimes AI clusters are in two different buildings. Natarajan Ramachandran, director of product line management for Broadcom’s Physical Layer Products Division, told EDN that Sian2M and Sian3 devices address these two scenarios, respectively.
Sian2M PHY chips
Ramachandran said that for shorter distances of less than 100 m, traditional optics, commonly termed multi-mode optics (MMF), is used. Here, vertical-cavity surface-emitting laser (VCSEL) technology has scaled very well so far. “However, in transition from 800 Gbps to 1.6 Tbps, VCSELs increasingly face physics limitations, making short-link bandwidths hugely constrained.”
Sian2M provides an optimized solution for 800G and 1.6T short-reach MMF links within AI clusters. It’s the first 200 G/lane DSP with integrated VCSEL drivers that enables low-power short-reach MMF links in AI clusters. “While industry watchers mostly believed that short link optics has reached a dead end, we are extending its life by at least one more generation,” Ramachandran said.
For longer distances of 2 Km to 3 Km operating across single-mode fiber (SMF) links, problems lie in power consumption. At 800 Gbps, power consumption was 15-16 W; but when you go to 1.6 Tbps, you don’t want to double the power usage. Enter Sian3 PHY chip.
Figure 2 Sian3 and Sian2M DSPs optimize power across single-mode fiber (SMF) and short-reach multi-mode fiber (MMF) links in 800G and 1.6T optical transceiver applications. Source: Broadcom
Sian3 PHY chips
At GTC 2025, held in San Jose, California, from 17 to 21 March, Nvidia’s chief Jensen Huang stressed the need for picojoule per bit to come down. That’s where Siam3 comes in, said Ramachandran. “We achieved 28 W with Sian2 while competition is roughly at 32 W,” he added. “With Siam3, a follow-on to Siam2, the transition from 5 nm to 3nm node results in 5-W savings, bringing power consumption down to 23 W.”
“So, we are getting close to what we’ve been consuming at 800 Gbps while moving to 1.6 Tbps speeds,” Ramachandran said. “And picojoule per bit is also showing a nice downward trend.” He also stated Broadcom’s aim to lower power consumption numbers, eventually reaching less than 20 W.
But is the cost also going down? Besides picojoule per bit, what about dollar per bit? Ramachandran said that with the transition from 5-nm to 3-nm process node, the die size also shrinks a lot, which significantly impacts the cost.
Broadcom is sampling Sian3 and Sian2M chips to early access customers and partners; Sian3 production is ramping up in the third quarter of 2025. Broadcom will demonstrate Sian chips and 200G VCSEL operating inside 1.6T optical modules at OFC in San Francisco, California, to be held on 1-3 April 2025.
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The post Optical PHYs facilitate 200G/lane speeds for AI clusters appeared first on EDN.
POET to demo light source and 1.6T optical engines for AI applications at OFC
Injection locking acts as a frequency divider and improves oscillator performance

Injection locking [1] can not only improve oscillator frequency stability and phase noise, but act as a selective frequency divider as well [2][3].
You can find sample setups of a simple two-transistor LC-based Peltz oscillator acting as a selective frequency divider in “Simple 5-component oscillator works below 0.8V” and “Investigating injection locking with DSO Bode function”.
Wow the engineering world with your unique design: Design Ideas Submission Guide
The oscillator in the setup and shown in Figure 1 is just a pair of 2N3904s, a 10 µH inductor, a 2.6 nF capacitor, and a 1K bias resistor operating from -2 V. This produces a ~1 MHz oscillator output.
Figure 1 The Peltz oscillator found in the “Simple 5-component oscillator works below 0.8V” design idea (DI) consisting of only 5 components.
Signal injection is by means of a series 10 KΩ and 0.01 µF RC connected to the common emitters of the Q1 and Q2 2N3906 transistors. The subtle non-linearities within the oscillator allow selective frequency locking and division without additional active components. Figure 2 shows examples of frequency division by 2, 3, 5, and 10 respectively without any component values or circuit changes!
Figure 2 Examples of frequency division by 2, 3, 5, and 10 without any changes to the component values or circuit, this is due to the subtle non-linearities within the oscillator that allow selective frequency locking and division.
Injection locking also improves the oscillator phase noise even when acting as a divider. Figure 3 shows some results from the free running oscillator and when acting as a frequency-selective divider.
Figure 3 Spectrum analysis of the oscillator free running and when acting as a frequency-selective divider with an injection-locked division of 3 and 10. There is a marked improvement in phase noise when acting as a frequency-selective divider.
The test setup used a general-purpose AWG (SDG2042X) as the signal source, a DSO (SDS814X HD) and spectrum analyzer (SSA3021X Plus) for the displays. Of course this technique isn’t going to replace a proper digital divider, but might find use in a pinch when one needs frequency division, or improve a simple oscillators stability and phase noise.
Michael A Wyatt is a life member with IEEE and has continued to enjoy electronics ever since his childhood. Mike has a long career spanning Honeywell, Northrop Grumman, Insyte/ITT/Ex-elis/Harris, ViaSat and retiring (semi) with Wyatt Labs. During his career he accumulated 32 US Patents and in the past published a few EDN Articles including Best Idea of the Year in 1989.
Related Content
- Simple 5-component oscillator works below 0.8V
- Investigating injection locking with DSO Bode function
- Ultra-low distortion oscillator, part 1: how not to do it.
- Ultra-low distortion oscillator, part 2: the real deal
- The Colpitts oscillator
- A two transistor sine wave oscillator
- Clapp versus Colpitts
References
- Razavi, B. “A study of injection pulling and locking in oscillators.” Proceedings of the IEEE 2003 Custom Integrated Circuits Conference, 2003., pp. 305–312, https://doi.org/10.1109/cicc.2003.1249409.
- “EEVblog Electronics Community Forum.” SMD Test Fixture for the Tektronix 576 Curve Tracer – Page 1, eevblog.com/forum/projects/smd-test-fixture-for-the-tektronix-576-curve-tracer/.
- “EEVblog Electronics Community Forum.” Injection Locked Peltz Oscillator with Bode Analysis – Page 1, www.eevblog.com/forum/projects/injection-locked-peltz-oscillator-with-bode-analysis/. Accessed 25 Mar. 2025.
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I had to switch some UART pins with some SPI pins to try a new microcontroller before printing new PCBs
![]() | submitted by /u/Patate-Furtif [link] [comments] |
Ds lite screen
![]() | Hey! I repaired the LCD ribbon cable in a Nintendo DS Lite. I know it’s completely not worth it since a new screen is super cheap, but I wanted to practice soldering and test my skills. And it actually worked! I intentionally placed a human hair on one of the pictures—for scale. I used an ultra-thin wire from a phone speaker coil to reconnect the traces. This was more of an experiment than a necessity, but the screen works like new, so mission accomplished. The photos are a bit blurry since I took them with my phone through a microscope eyepiece—I don’t have a proper adapter. All this effort for something that costs just a few bucks—but the satisfaction is priceless! [link] [comments] |
Sivers collaborating with WIN to scale high-volume DFB laser production
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