Battlebots 2018 & the Hardcore Robotics Team – #27

“I tend to not turn Tombstone on outside of the arena – it scares the crap out of me.” – Ray Billings, Hardcore Robotics team captain. We sit down with BattleBots’ resident bad boy to talk about the engineering behind the world’s meanest fighting robots. We also talk robot carnage. Because we know you’re really here for robot carnage.

“I tend to not turn Tombstone on outside of the arena. It scares the crap out of me…” – Ray Billings, Hardcore Robotics team captain. We sit down with BattleBots’ resident bad boy to talk about the engineering behind the world’s meanest fighting robots. We also talk robot carnage. Because we know you’re really here for robot carnage.


00:03 Ray Billings leads the Hardcore Robotics Battlebots team, and is the “resident villain” on Battlebots.

00:40 Mike went to high school with Ray’s son

01:15 Ray’s robot, “Tombstone” is ranked #1 on the Battlebots circuit. Highlights here.

1:34 The winner trophy for Battlebots is a giant nut.

2:00 Ray doesn’t turn on the robot very often outside of the arena

2:35 Ray’s carnage story: he bent a 1” thick titanium plate

3:20 You have to see combat robots live to get the full experience

4:10 The first match of Battlebots 2018 should be one of the most epic Battlebots fights of all time

4:30 Ray has done over 1,000 combat robot matches in 17 years

5:00 How Ray got into Battlebots

6:25 The main robot is called an offset horizontal spinner. It spins a 70-75 lb bar at 2500 rpm.

7:40 The body is 4130 choromoly tubing. The drive motors were intended for an electric wheelchair, and the weapons motor is from an electric golf cart.

8:20 Normal electrical motors are not designed to work for combat robots. Ray significantly stresses the motors.

8:50 The weapon motor was designed to be used at 48V 300A, but Ray uses it at 60V and 1100A (at spinup). This would overheat and destroy the motor, so it shouldn’t be done long-term.

9:40 – 70-80kW at spinup, and no start capacitor. He just uses a big marine relay.

10:00 Ray’s robot has 1 second to be lethal

10:30 If there’s a motor-stall potential mid match, Ray will turn off the motor to save batteries/electronics

11:00 What’s the weak point of Ray’s robot? One match, the weapon bar snapped in half.

11:40 Ray uses tool-grade steel, so it won’t bend, it’ll just snap.

12:40 The shock loads can break the case. The weapon motor looks like it’s rigidly mounted, but because it’s on a titanium plate it has some shock absorber. There’s also a clutch system in the sprocket to help offset shock.

13:40 Ray’s robot has to take all of the force that the opponent’s robots do (equal and opposite), but if it’s coming in a direction you want vs. one you don’t want you can design-in protection.

14:40 What test challenges were faced during assembly and design?

It’s been highly iterated. There are no shortcuts for designing combat robots. You have to see where something breaks, then adjust.

15:45 When Ray started in 2004, his robot was just a “middle of the pack” robot. With years of iteration, it’s now a class-dominant robot.

16:45 Ray spins up the robot at least once before a competition. It’ll pick up debris from the ground and throw it around.

17:50 Battery technology and batteries for combat robots: Originally they used lead acid batteries for their current ability. Now, almost everyone uses Lithium chemistry. The sport is about power-to-weight ratio, so the lighter batteries have given people much more flexibility.

19:00 Why aren’t there gas powered combat robots? There are some that have flamethrowers, and there are a couple gas powered ones. However, they aren’t as dependable.

20:15 Ray has wrecked arenas. The arena rails are 1/2” steel, and Ray can cut a soda-can sized hole in them. He’s wrecked panels and ceiling lights.

21:20 Combat robot communication systems: today everything runs on 2.4 GHz digitally encoded systems. They often use RC plane controls because they are highly customizable and there are a lot of available channels.

22:00 Drive systems: the wheels & motors come together. They use a hard foam in the tires so you can’t get a flat.

22:45 Centrifugal force – not a huge problem because the blade spins in-plane. But, when he gets bumped up the blade fights gravity before it can self-right.

24:40 The rest of the Hardcore Robotics team is three people.. The team is Ray, his son (Justin), and his friend Rick. Rick used to run his own team, but has more fun fabricating and building robots than he does driving them.

25:30 There will be 6 fights/hour, and the show will be on the Discovery channel and the science channel premiering May 11th.

26:15 The first fight got leaked in some promo footage, Tombstone vs. Minotaur.

26:35 Would Ray rather fight a good robot or a bad one? Ray says “anyone.”

Battlebots 2018 (season 3) will have “fight card” fights, then a playoff of the top 16 robots.

27:50 A given frame only lasts an event or two before needing to be replaced. This many fights is really hard on the robot.

29:20 Combat robot kits are a great way to get into the sport, especially ant-weight and beetle weight kits.

30:00 Stupid questions

31:15 Ray wants to try a new hammer robot, a full-shell spinner, and a vertical spinner.

32:40 Support Ray by getting Hardcore Robotics gear from and the toys from Target, Amazon, hexbugs, etc.

33:15 Ray is also an engineer at Intel.

Secret Specs, LPDDR5, and Interposers – #26

Keeping specs secret is just part of the job. Getting a usable, working spec is another. Learn why JEDEC guards a spec, the basic DDR architecture, and geek out with us about the challenges of probing DDR.

Hosted by Daniel Bogdanoff and Mike Hoffman, EEs Talk Tech is a twice-monthly engineering podcast discussing tech trends and industry news from an electrical engineer’s perspective.

Keeping specs secret is just part of the job. Getting a usable, working spec is another. We sat down with Jennie Grosslight to learn why JEDEC guards a spec, the basic DDR architecture, and geek out  about the challenges of probing DDR.

Hosted by Daniel Bogdanoff and Mike Hoffman, EEs Talk Tech is a twice-monthly engineering podcast discussing tech trends and industry news from an electrical engineer’s perspective.




How are electrical engineering and protocol specifications defined?

Bigger companies tend to drive specifications because they can afford to put money into new products

Sometimes small or midsize companies with an idea can make something new happen, but they have to push it

Most memory technologies have a couple players:
1. The chipset and the memory controller industry
2. The actual devices that store data (DRAM)

There’s a tremendous amount of work between all the players to make all the parts work together.

Why JEDEC keeps information about new products private as they’re being developed:
If you spread your information too wide then you can get a lot of misinformation. Fake news!
Early discussions also might not resemble the end product

DDR5, LPDDR, and 3D silicon die stacking are new and exciting in memory

We keep pushing physics to new edges

Heat management in 3D silicon is a big challenge

LPDDR5 is the new low power memory for devices like cell phones and embedded devices

5G devices will likely depend on low power memory

Once the RF challenges of 5G are figured out there will be even more challenges on the digital side. Systems have to deal with large bandwidths and low latencies

Higher performance and lower power is driving development of LPDDR5

It will be interesting to see if improvements are made in jumps or very slowly

Dropping voltage swing and increasing speed both make the eye smaller
Making the eye smaller makes you more vulnerable to crosstalk

12:20 – Completely closed eyes for DDR5

How to probe DDR?
We use a lot of simulation because the circuits are so sensitive

Crosstalk is often a problem when making DDR and LPDDR measurements

Economics drives everything so new technology is often based on existing systems

What comes next is up to who comes up with the best idea

What will drive change is when the existing materials can no longer meet performance

Power is important for big data farms as well as cell phones


Chipset rank on a DIMM

The pieces share a common data bus so you need to know the order to properly test

DIMM interposer used for logic measurements for servers

With a scope a ball grid array is used under a device or the pins are probed

Oscilloscope interposers are available that work similarly to the logic analyzer interposers

The logic analyzer looks at all the signals at once, typically the oscilloscope only looks at a few

When testing you want to validate that the device followed the protocal in the right sequence

Data rates of DDR

DDR5 is supposed to get to 6400 MT/s


DDR5 and 3D Silicon – #25

DDR5 marks a huge shift in thinking for traditional high-tech memory and IO engineering teams. The implications of this are just now being digested by the industry, and opening up doors for new technologies. In today’s electrical engineering podcast, Daniel Bogdanoff and Mike Hoffman sit down with Perry Keller to discuss how engineers should “get their game on” for DDR5.

“You reach critical certain thresholds that are driven by the laws of physics and material science” – Perry Keller

DDR5 marks a huge shift in thinking for traditional high-tech memory and IO engineering teams. The implications of this are just now being digested by the industry, and opening up doors for new technologies. In today’s electrical engineering podcast, Daniel Bogdanoff and Mike Hoffman sit down with Perry Keller to discuss how engineers should “get their game on” for DDR5.



Sign up for the DDR5 Webcast with Perry on April 24, 2018!


00:20 Getting your game on with DDR5

LPDDR5 6.4 gigatransfers per second (GT/s)

“You reach critical certain thresholds that are driven by the laws of physics and material science” – Perry Keller

1:00 We’re running into the limits of what physics allows

2:00 DDR3 at 1600 – the timing budget was starting to close.

2:30  With DDR5, a whole new set of concepts need to be embraced.

3:00 DesignCon is the trade show – Mike is famous for his picture with ChipHead

4:00 Rick Eads talked about DesignCon in the PCIe electrical engineering podcast

4:40 The DDR5 paradigm shift is being slowly digested

4:50 DDR (double data rate) introduced source synchronous clocking

All the previous memories had a system clock that governed when data was transferred.

Source synchronous clocking is when the system controlling the data also controls the clock. Source synchronous clocking is also known as forward clocking.

This was the start of high speed digital design.

At 1600 Megatransfers per second (MT/s), this all started falling apart.

For DDR5, you have to go from high speed digital design concepts to concepts in high speed serial systems, like USB.

The reason is that you cant control the timing as tightly. So, you have to count on where the data eye is.

As long as the receiver can follow where that data eye is, you can capture the information reliably.

DRAM doesn’t use an embedded clock due to latency. There’s a lot of overhead, which reduces channel efficiency

DDR is single ended for data, but over time more signals become differential.

You can’t just drop High Speed Serial techniques into DDR and have it work.

The problem is, the eye is closed. The old techniques won’t work anymore.

DDR is the last remaining wide parallel communication system.

There’s a controller on one end, which is the CPU. The other end is a memory device.

With DDR5, the eye is closed. So, the receiver will play a bigger part. It’s important to understand the concepts of equalizing receivers.

You have to think about how the controller and the receiver work together.

Historically, the memory folks and IO folks have been different teams. The concepts were different. Now, those teams are merging

DDR5 is one of the last steps before people have to start grappling with communication theory. Modulation, etc.

Most PCs now will have two channels of communication that’s dozens or hundreds of bits wide.

What is 3D silicon?

If 3D silicon doesn’t come through, we’ll have to push more bits through copper.

3D silicon is nice because you can pack more into a smaller space.

3D silicon is multiple chips bonded together. Vias connect through the chips instead of traces.

The biggest delay for 3D silicon is that it turns on its head the entire value delivery system.

7 years ago, JEDEC started working on wide IO

What’s the difference between 3D silicon and having it all built right into the processor?

It’s the difference between working in two dimensions and three dimensions. If you go 3D, you can minimize footprint and connections

Flash memory, the big deal has been building multiple active layers.

The ability to stack would be useful for mobile.

Where is technology today with DDR?

DDR4 is now mainstream, and JEDEC started on DDR5 a year ago (2017)

Memory, DDR5+, and JEDEC – #24

“It’s a miracle it works at all.” In this electrical engineering podcast, we discuss the state of memory today and it’s inevitable march into the future.

Hosted by Daniel Bogdanoff and Mike Hoffman, EEs Talk Tech is a twice-monthly engineering podcast discussing tech trends and industry news from an electrical engineer’s perspective.

“It’s a miracle it works at all.” Not the most inspiring words from someone who helped define the latest DDR spec. But, that’s the the state of today’s memory systems. Closed eyes and mV voltage swings are the topic of today’s electrical engineering podcast. Daniel Bogdanoff (@Keysight_Daniel) and Mike Hoffman sit down with Perry Keller to talk about the state of memory today and it’s inevitable march into the future.


00:00 Today’s guest is Perry Keller, he works a lot with standards committees and making next generation technology happen.

00:50 Perry has been working with memory for 15 years.

1:10 He also did ASIC design, project management for software and hardware

Perry is on the JEDEC board of directors

JEDEC is one of the oldest standards body, maybe older than IEEE

1:50 JEDEC was established to create standards for semiconductors. This was an era when vacuum tubes were being replaced by solid state devices.

2:00 JEDEC started by working on instruction set standards

2:15 There are two main groups. A wide bandgap semiconductors group and a memory group.

3:00 Volatile memory vs. nonvolatile memory. An SSD is nonvolatile storage, like in a phone. But if you look at a DIMM in a PC that’s volatile.

3:40 Nonvolatile memory is everywhere, even in light bulbs.

4:00 Even a DRAM can hold its contents for quite some time. JEDEC had discussions about doing massive erases because spooks will try to recover data from it.

DRAM uses capacitors for storage, so the colder they are the longer they hold their charge.

4:45 DRAM is the last vestige of the classical wide single ended parallel bus. “It’s a miracle that it works at all.”

5:30 Perry showed a friend a GDDR5 bus and challenged him to get an eye on it and he couldn’t.

6:10 Even though DDR signals look awful, it depends on reliable data transfer. The timing and clocking is set up in a way to deal with all of the various factors.

7:00 DDR specifications continue to march forward. There’s always something going on in memory.

8:00 Perry got involved with JEDEC through a conversation with the board chairman.

8:35 When DDR started, 144 MT/s (megatransfers per second) was considered fast. But, DDR5 has and end of life goal of 6.5 GT/s on a 80+ bit wide single ended parallel bus.

9:05 What are the big drivers for memory technology? Power. Power is everything. LPDDR – low power DDR – is a big push right now.

9:30 if you look at the memory ecosystem, the big activity is in mobile. The server applications are becoming focused with the cloud, but the new technology and investment is mobile.

10:00 If you look at a DRAM, you can divide it into three major categories. Mainstream PC memory, low power memory, and GDDR. GDDR is graphics memory. The differences are in both power and cost.

For example, LPDDR is static designs. You can clock it down to DC, which you can’t do with normal DDR.

The first DDR was essentially TTL compatible. Now, we’re looking at 1.1V power supplies and voltage swings in the mV.

Semiconductor technology is driving the voltages down to a large degree.

11:45 DRAM and GDDR is a big deal for servers.

A company from China tried to get JEDEC to increase the operating temperature range of DRAMs by 10 C. They fire up one new coal fired power plant per week in China to meet growing demand. They found they could cut it down to only 3 per month with this change in temperature specs.

13:10 About 5 years ago, the industry realized that simply increasing I/O speeds wouldn’t help system performance that much because the core memory access time hasn’t changed in 15 years. The I/O rate has increased, but basically they do that by pulling more bits at once out of the core and shifting them out. The latency is what really hurts at a system level.

14:15 Development teams say that their entire budget for designing silicon is paid for out of smaller electric bills.

15:00 Wide bandgap semiconductors are happy running at very high temperatures. If these temperatures end up in the data centers, you’ll have to have moon suits to access the servers.

16:30 Perry says there’s more interesting stuff going on in the computing than he’s seen in his whole career.

The interface between different levels is not very smooth. The magic in a spin-up disk is in the cache-optimizing algorithms. That whole 8-level structure is being re-thought.

18:00 Von Neumann architectures are not constraining people any more.

18:10 Anything that happens architecturally in the computing world affects and is affected by memory.

22:10 When we move from packaged semiconductors to 3D silicon we will see the end of DDR. The first successful step is called high bandwidth memory, which is essentially a replacement for GDDR5.

23:00 To move to a new DDR spec, you basically have to double the burst size.

Data Analytics for Engineering Projects – #23

Learn some best practices for engineering projects that have huge amounts of data. Data analytics tools are crucial for project success! Listen in on today’s EEs Talk Tech electrical engineering podcast.

It seems most large labs have a go-to data person. You know, the one who had to upgrade his PC so it could handle insanely complex Excel pivot tables? In large electrical engineering R&D labs, measurement data can often be inaccessible and unreliable.

In today’s electrical engineering podcast, Daniel Bogdanoff (@Keysight_Daniel) sits down with Ailee Grumbine and Brad Doerr to talk about techniques for managing test & measurement data for large engineering projects.



1:10 – Who is using data analytics?

2:00 – for a hobbyist in the garage, they may still have a lot of data. But, because it’s a one-person team, it’s much easier to handle the data.

Medium and large size teams generate a lot of data. There are a lot of prototypes, tests, etc.

3:25 – The best teams manage their data efficiently. They are able to make quick, informed decisions.

4:25 – A manager told Brad, “I would rather re-make the measurements because I don’t trust the data that we have.”

6:00 – Separate the properties from the measurements. Separate the data from the metadata. Separating data from production lines, prototype units, etc. helps us at Keysight make good engineering decisions.

9:30 – Data analytics helps for analyzing simulation data before tape out of a chip.

10:30 – It’s common to have multiple IT people managing a specific project.

11:00 – Engineering companies should use a data analytics tool that is data and domain agnostic.

11:45 – Many teams have an engineer or two that manage data for their teams. Often, it’s the team lead. They often get buried in data analytics instead of engineering and analysis work. It’s a bad investment to have engineers doing IT work.

14:00 – A lot of high speed serial standards have workshops and plugfests. They test their products to make sure they are interoperable and how they stack up against their competitors.

15:30 – We plan to capture industry-wide data and let people see how their project stacks up against the industry as a whole.

16:45 – On the design side, it’s important to see how the design team’s simulation results stack up against the validation team’s empirical results.

18:00 – Data analytics is crucial for manufacturing. About 10% of our R&D tests make it to manufacturing. And, manufacturing has a different set of data and metrics.

19:00 – Do people get hired/fired based on data? In one situation, there was a lack of data being shared that ended up costing the company over $1M and 6 months of time-to-market.




Radar and Electronic Warfare

Learn about radar basics and get a peek into the world of aerospace electronic warfare. Hosted by Daniel Bogdanoff and Mike Hoffman, EEs Talk Tech is a twice-monthly engineering podcast discussing tech trends and industry news from an electrical engineer’s perspective.

Phil Gresock, Keysight’s Radar Lead, sits down with us to discuss the basics of radar and give us a peek into the world of aerospace electronic warfare.


00:20 Adaptive cruise control for cars works really well.

1:00 the history of radar – the original radar display was an oscilloscope in WWII. (radar test equipment)

1:45 Early warning radar

2:00 The rumor that carrots are good for your eyesight was a British misinformation campaign.

2:58 The British had the “chain home radar system” all along the coast that pointed to their western front. They wanted early warning radar because they had limited defensive forces. By knowing what was coming, they could allocate defenses appropriately.

3:45 Radar originally was a defensive mechanism.

3:50 How does radar work? You send out a pulse that is modulated on a carrier frequency. If that pulse gets reflected back, we can do some math and work out how far away something is.

4:30 Typically, there’s a specific frequency used. For long range radar, like search and early warning radar, a lower frequency is used.

5:15 What does a modern radar system look like?

It depends on the application. Early warning systems are often anchored on old oil rigs. The rigs have a radome installed on them.

6:25 How does radar detect something so small and so far away? A lot of it depends on the frequencies and processing techniques you use.

6:40 There are some radar techniques you can use, for example bouncing off of the sea, the earth, the troposphere.

7:15 Radar also has some navigational benefits. For example, wind shear flying into Breckenridge airport. A change in medium is measurable.

8:10 Radars also get installed on missiles to do some last-minute corrections.

8:35 Ultimately, the goal of radar is to detect something. You’re trying to figure out range, elevation (azimuth), velocity, etc.

Different target sizes and ranges require different pulse widths, different frequencies, etc.

Azimuth is easy to determine because you know what direction your radar is pointing.

To detect velocity with radar you can use doppler shift.

10:30 Radar cross section analysis gives even more information.

11:00 There are spheres in space for radar calibration. You can send pulses to the sphere and measure what you get back.

Radar calibration sphere in low earth orbit: (for full paper, click the “full text” link)

11:40 There are also reflectors on the moon so you can use laser telescopes to measure the reflection.

Mirrors on the moon:

12:30 NASA put reflectors in space.

12:58 So, you send a pulse out and get a return signal, but there was a scattering effect. There are libraries for what a return pulse for different objects looks like so you can identify what you are looking at.

14:00 Radar counter intelligence techniques.

First, you have to know you are being painted by radar. Military jets have a number of antennas all around it. And, you generally know what radars are being used in a theater of operation. So, there will be a warning that will let you know you are being painted by a certain type of radar.

15:30 Get Daniel on a fighter jet

16:05 How do you stop your radar from being detected or interfered with? There are a few techniques.

Radar frequency hopping is changing the frequency used from pulse to pulse.

Radar frequency modulation changes the modulation pulse to pulse – phase shifts, amplitude changes, frequency chirps, etc.

This helps avoid detection, get better performance, or reduce susceptibility to jamming.

If you know how your radar responds to different signals, you have a lot of flexibility in what signal you use.

How do you spoof a radar? You have to know what is incident upon you and know how that will act over time. You can send out pulses advanced or lagging in time or with different Doppler shifts to give misinformation to the receiver.

You can also drown out the pulses so that your pulses get read instead of your reflections.

You have to have an intimate understanding of the radar you’re trying to defeat, a good system to handle that quickly, and good knowledge that something is actually happening.

We need radar profile flash cards.

Radar peak energies are anywhere from kilowatts to Megawatts.

21:10 A recent US Navy ship had a new hull design, and it has to turn on a beacon because it had so little reflections.

22:00 Phil thinks radars are pretty cool, and it shows up in a lot more places than you’d expect.

Radar stands for “radio detection and ranging.”


Intro to RF – EEs Talk Tech Electrical Engineering Podcast #21

Learn about RF designs, radio frequencies, RADAR, GPS, and RF terms you need to know in today’s electrical engineering podcast!

We sit down with Phil Gresock to talk about the basics of RF for “DC plebians.” Learn about RF designs, radio frequencies, RADAR, GPS, and RF terms you need to know in today’s electrical engineering podcast!



RF stands for radio frequency

00:40 Phil Gresock was an RF application engineer

1:15 Everything is time domain, but a lot of RF testing tools end up being frequency domain oriented

2:15 Think about radio, for example. A tall radio tower isn’t actually one big antenna!

3:50 Check out the FCC spectrum allocation chart

4:10 RF communication is useful when we want to communicate and it doesn’t make sense to run a cable to what we’re communicating to.

4:50 When you tune your radio to a frequency, you are tuning to a center frequency. The center frequency is then down converted into a range

6:30 Check out Mike’s blog on how signal modulation works:

7:00 Communication is just one use case. RADAR also is an RF application.

8:10 The principles between RF and DC or digital use models are very similar, but the words we use tend to be different.

Bandwidth for oscilloscopes means DC to a frequency, but for RF it means the analysis bandwidth around a center frequency

9:22 Cellular and FCC allocation chart will talk about different “channels.”

Channel in the RF world refers to frequency ranges, but in the DC domain it typically refers to a specific input.

10:25 Basic RF block diagram:

First, there’s an input from an FPGA or data creating device. Then, the signal gets mixed with a local oscillator (LO). That then connects to a transmission medium, like a fiber optic cable or through the air.

Cable TV is an RF signal that is cabled, not wireless.

Then, the transmitted signal connects to an RF downcoverter, which is basically another mixer, and that gets fed into a processing block.

13:50 Tesla created a remote control boat and pretended it was voice controlled.

15:30 Does the military arena influence consumer electronics, or does the consumer electronics industry influence military technology?

16:00 GPS is a great example of military tech moving to consumer electronics

17:00 IoT (internet of things) is also driving a lot of the technology

18:00 The ISM band is unregulated!

19:15 A router uses a regulated frequency and hops off the frequency when it’s being used for emergency communications

20:50 RADAR, how does it work?

22:22 To learn more about RF, check out App Note 150 here:




Wide Bandgap Semiconductors for Power Electronics – Electrical Engineering Podcast #20

Wide bandgap semiconductors, like Gallium Nitride (GaN) and Silicon Carbide (SiC) are shaping the future of power electronics by boosting power efficiency and reducing physical footprint. Server farms, alternative energy sources, and electrical grids will all be affected!

Wide bandgap semiconductors, like Gallium Nitride (GaN) and Silicon Carbide (SiC) are shaping the future of power electronics by boosting power efficiency and reducing physical footprint. Server farms, alternative energy sources, and electrical grids will all be affected! Mike Hoffman and Daniel Bogdanoff sit down with Kenny Johnson to discuss in today’s electrical engineering podcast.



Fact Sheet:

Fact Sheet

Tech Assessment (Good timeline information)

Agenda – Wide Bandgap Semiconductors

Use in Power Electronics

3:00 What is a wide bandgap semiconductor? GaN (Gallium Nitride) devices and SiC (Silicon Carbide) can switch on and off much faster than typical silicon power devices. Wide bandgap semiconductors also have better thermal conductivity. And, wide bandgap semiconductors have a significantly lower drain-source resistance (R-on).
For switch mode power supplies, the transistor switch time is the key source of inefficiency. So, switching faster makes things more efficient.

4:00 They will also reduce the size of power electronics.

6:30 Wide bandgap semiconductors have a very fast rise time, which can cause EMI and RFI problems. The high switching speed also means they can’t handle much parasitic inductance. So, today’s IC packaging technology isn’t ideal.

8:30 Wide bandgap semiconductors are enabling the smart grid. The smart grid essentially means that you only turning on things being used, and turning off power completely when they aren’t being used.

9:35 Wide bandgap semiconductors will probably be integrated into server farms before they are used in power grid distribution or in homes.

10:20 Google uses a lot of power. 2.3 TWh (terawatt hour)
NYT article:

It’s estimated Google has 900,000 servers, and that accounts for maybe 1% of the world’s servers.
So, they are willing to put in the investment to work out the details of this technology.

11:50 The US Department of Energy wants people to get an advanced degree in power electronics. Countries want to have technology leadership in this area.

13:00 Wide bandgap semiconductors are also very important for wind farms and other alternative forms of energy.

Having a solid switch mode power supply means that you don’t have to have extra capacity.

USA Dept of Energy: If industrial motor systems were wide bandgap semiconductors took over, it would save a ton of energy.

14:45 A huge percentage of the world’s power is consumed by electrical pumps.

16:20 Kenny’s oldest son works for a company that goes around and shows companies how to recover energy costs.

There aren’t many tools available for measuring wide bandgap semiconductor power electronics.

19:30 Utilities and servers are the two main industries that will initially adopt wide band gap semiconductors

20:35 When will this technology get implemented in the real world? There are parts available today, but it probably won’t be viable for roughly 2-5 years.

21:00 Devices with fast switching are beneficial, but have their own set of problems. The faster a devices switches, the more EMI and RFI you have to deal with.

Spread spectrum clocking is a technique used to pass EMI compliance.

24:00 Band gaps of different materials: Diamond 5.5 eV Gallium Nitride (GaN) 3.4 eV Silicon Carbide (SiC) 3.3 eV

Power Integrity and Signal Integrity – Electrical Engineering Podcast #19

Learn about power integrity and signal integrity in this electrical engineering podcast. Power integrity will impact signal integrity, EMI, and EMC! We sit down with Kenny Johnson to discuss.

Hosted by Daniel Bogdanoff and Mike Hoffman, EEs Talk Tech is a twice-monthly engineering podcast discussing tech trends and industry news from an electrical engineer’s perspective.

How’s the impedance of your ground plane? Do you look at your power rails in the frequency domain? Mike Hoffman and Daniel Bogdanoff sit down with power integrity expert Kenny Johnson to discuss the latest trends and techniques for measuring power supplies in today’s electrical engineering podcast.

00:15 Kenny gave us a tip during scope month

01:26 There are two types of power people.

There are power producers, like the wind farms, power plants, and AC/DC adapter creators

There are power consumers, who care very much about their power quality. The ripple on power supplies, etc.

3:03 Power integrity is the study of the effectiveness of the conversion and delivery of DC power from the source to the gates on the IC.

3:45 If Moore’s Law holds out for another 600 years, we will have a computer that is capable of simulating every atom in the known universe.

4:35 Thermal hotspots were causing problems, so voltage levels started dropping

5:00 Kenny went to Amazon to look for a power integrity book. There were only 2-3 books a few years ago

Power integrity has been a thing since the 1930s

5:50 Product functional reliability is directly proportional to the power quality in a product.

We’re supplying a voltage to devices, but also current. So, this starts to look a lot like Ohm’s law.

A device has both power and a ground plane.

Power integrity pioneers include Istvan Novak and Ray Ridley and they talk about flat impedance power planes.

7:15 Flat impedance power planes – divide the supply power by the peak current, multiply it by your tolerance, you get a target impedance for your power planes.

If you can maintain a frequency flat impedance, you don’t see noise on your power supplies.

7:55 Think back to circuits 101, an inductor is open at a high frequency. And, a power plane is basically a big inductor. If you are, for example, writing high speed digital data to memory, it will be a problem.

8:40 When you look at boards, you see bypass capacitors to counteract the inductors

10:30 Experienced engineers use a lot of intuition when working out power distribution. Now, there’s a lot of localized power distribution.

11:15 A typical SSD has 12 power supplies

A tablet can have 50 power supplies

Some of our oscilloscopes have 180 power supply rails

Next generation mobile electronics 100-200 power supplies

12:25 There are redundant power supplies spread out across the device to help improve reliability. For example, there may be multiple converters that all power the same rail to help spread the loads.

The reason intuition is used is that a lot of people don’t have access to good simulation tools. They just have to use some rules of thumb and over-engineer the device to try to get reliability.

15:10 Kenny has a lot of patents. Our CTO Jay Alexander used to hold the record for most patents at the Colorado Springs site. Kenny has nearly 30 patents.

17:15 Kenny started as a probe designer, then got into power integrity.

Kenny recommends one by Bogatin about signal integrity, and a second edition called Signal Integrity and Power Integrity

18:35 SIPI labs – signal integrity and power integrity lab. Power integrity will affect your signal integrity, your EMI (electromagnetic interference) and your EMC (electromagnetic compatibility). (measure power integrity with a power rail probe)

So, the progressive companies have these SIPI labs. There are more advanced tools available.

20:10 Multiple papers say that power supply induced jitter is the single biggest source of data jitter in a digital system.

Kenny has some IOT development kits, and it’s easy to make them drop bits. Dropping bits will have an effect on battery life, performance, etc.

21:08 How to clean up a power supply? The majority of the time, it’s easiest to use a bypass capacitor. After you’ve looked at your supply in the time domain, look at it in the frequency domain. That will help you debug where the noise is coming from. And, if you know the frequency you are having trouble with, you can work backward into a bypass capacitor

22:42 There are some general rules that seem to apply to everything in electronics. Closer to the device is always better.

Next podcast – wide bandgap! The US Department of Energy will pay for some people to go back to university and get a degree in power engineering. Wide bandgap semiconductors have a huge potential to reduce energy usage.


PAM4 and 400G – Ethernet #18

Learn how PAM4 is allowing some companies to double their data rate – and the new challenges this brings up for engineers. (electrical engineering podcast)

Today’s systems simply can’t communicate any faster. Learn how some companies are getting creative and doubling their data rates using PAM4 – and the extra challenge this technology means for engineers.

Mike Hoffman and Daniel Bogdanoff sit down with PAM4 transmitter expert Alex Bailes and PAM4 receiver expert Steve Reinhold to discuss the trends, challenges, and rewards of this technology.


PAM isn’t just cooking spray.

What is PAM4? PAM stands for Pulse Amplitude Modulation, and is a serial data communication technique in which more than one bit of data can be communicated per clock cycle. Instead of just a high (1) or low (0) value, a in PAM4, a voltage level can represent 00, 01, 10, or 11. NRZ is essentially just PAM2.

We are reaching the limit of NRZ communication capabilities over the current communication channels.

2:10 PAM has been around for a while, it was used in 1000BASE-T. 10GBASE-T uses PAM16, which means it has 16 different possible voltage levels per clock cycle. It acts a bit like an analog to digital converter.

2:55 Many existing PAM4 specifications have voltage swings of 600-800 mV

3:15 What does a PAM4 receiver look like?  A basic NRZ receiver just needs a comparator, but what about multiple levels?

3:40 Engineers add multiple slicers and do post-processing to clean up the data or put an ADC at the receiver and do the data analysis all at once.

PAM4 communicates 2-bits per clock cycle, 00, 01, 10, or 11.

4:25 Radio engineers have been searching for better modulation techniques for some time, but now digital people are starting to get interested.

4:40 With communications going so fast, the channel bandwidth limits the ability to transmit data.

PAM4 allows you to effectively double your data rate by doubling the amount of data per clock cycle.

5:05 What’s the downside of PAM4? The Signal to Noise Ratio (SNR) for PAM4  worse than traditional NRZ. In a perfect world, the ideal SNR would be 9.6 dB (for four levels instead of two). In reality, it’s worse, though.

5:30 Each eye may not be the same height, so that also has an effect on the total SNR.

6:05 What’s the bit error ratio (BER) of a PAM4 vs. NRZ signal if the transmission channel doesn’t change?

6:45 The channels were already challenged, even for many NRZ signals. So, it doesn’t look good for PAM4 signals. Something has to change.

7:00 PAM4 is designed to operate at a high BER. NRZ typically specified a 1E-12 or 1E-15 BER, but many PAM4 specs are targeting 1E-4 or 1E-5. It uses forward error correction (or other schemes) to get accurate data transmission.

7:50 Companies are designing more complex receivers and more robust computing power to make PAM4 work. This investment is worth it because they don’t have to significantly change their existing hardware.

8:45 PAM is being driven largely by Ethernet. The goal is to get to a 1 Tb/s data rate.

9:15 Currently 400 GbE is the next step towards the 1 Tbps Ethernet rate (terabit per second).

10:25 In Steve’s HP days, the salesmen would e-mail large pictures (1 MB) to him to try to fill up his drive.

11:10 Is there a diminishing rate of return for going to higher PAM levels?

PAM3 is used in automotive Ethernet, and 1000BASE-T uses PAM5.

Broadcom pushed the development of PAM3. The goal was to have just one pair of cables going through a vehicle instead of the 4 pairs in typical Ethernet cables.

Cars are an electrically noisy environment, so Ethernet is very popular for entertainment systems and less critical systems.

Essentially, Ethernet is replacing FlexRay. There was a technology battle for different automotive communication techniques. You wouldn’t want your ABS running on Ethernet because it’s not very robust.

14:45 In optical communication systems there is more modulation, but those systems don’t have the same noise constraints.

For digital communications, PAM8 is not possible over today’s channels because of the noise.

15:20 PAM4 is the main new scheme for digital communications

15:50 Baseband digital data transmission covers a wide frequency range. It goes from DC (all zeroes or all ones) to a frequency of the baud rate over 2 (e.g. 101010). This causes intersymbol interference (ISI) jitter that has to be corrected for – which is why we use transmitter equalization and receiver equalization.

16:55 PAM4 also requires clock recovery, and it is much harder to recover a clock when you have multiple possible signal levels.

17:35 ISI is easier to think about on an NRZ signal. If a signal has ten 0s in a row, then transitions up to ten 1s in a row,  the channel attenuation will be minimal. But, if you put a transition every bit, the attenuation will be much worse.

19:15 To reduce ISI, we use de-emphasis or pre-emphasis on the transmit side, and equalization on the receiver side. Engineers essentially boost the high frequencies at the expense of the low frequencies. It’s very similar to Dolby audio.

20:40 How do you boost only the high frequencies? There are circuits you can design that react based on the history of the bit stream. At potentially error-inducing transition bits, this circuitry drives a higher amplitude than a normal bit.

22:35 Clock recovery is a big challenge, especially for collapsed eyes. In oscilloscopes, there are special techniques to recover the eye and allow system analysis.

With different tools, you can profile an impulse response and detect whether you need to de-emphasize or modify the signal before transmission. Essentially, you can get the transfer function of your link.

23:45 For Ethernet systems, there are usually three equalization taps. Chip designers can modify the tap coefficients to tweak their systems and get the chip to operate properly. They have to design in enough compensation flexibility to make the communication system operate properly.

25:00 PAM vs. QAM? Is QAM just an RF and optical technique, or can it be used in a digital system?

25:40 Steve suspects QAM will start to be used for digital communications instead of just being used in coherent communication systems.

26:30 PAM4 is mostly applicable to the 200 GbE and 400 GbE, and something has to have to happen for us to get faster data transfer.

26:48 Many other technologies are starting to look into PAM4 – InfiniBand, Thunderbolt, and PCIe for example.

You can also read the EDN article on PAM4 here. If you’re working on PAM4, you can also check out how to prepare for PAM4 technology on this page.