Lee Ritchey On the Future of PCB Design

Estimated reading time: 17 minutes

Ritchey: Yes. If you go back to when I graduated from university, companies had programs and the nickname was “kiddie engineers.” For example, at Tektronix, in your first six months you worked on a small project where you did everything all over the company. So you knew what purchasing had to do and all that business, and you were tutored by a senior engineer. That all went away when Silicon Valley exploded, because we did not have time to train anybody. You had to hire somebody who already knew it and so that all went away. Now it's coming back. But Motorola had kiddie engineers and Tektronix and HP did as well.

Matties: There have been a lot of advancements in EDA tools also. You are seeing a lot more thinking embedded in the tools.

Ritchey: Well, actually that's not quite true.

Matties: Really?

Ritchey: I like to use an example. You may remember Amdahl computers? That was the first computer that competed directly with IBM and it was in Silicon Valley. I was there, and we had a press conference. Lots of fanfare and this was a big computer and all that business and here was a question that was asked in the Q&A. This reporter asked, "Mr. Amdahl, aren't you afraid you're making computers so smart they'll replace thinking?" He said, "What you don't understand, ma'am, is what we have here is an exceedingly fast idiot." This is what all the tools are. There's no smarts in the tools. They let you do analysis quicker, but if you don't have the technical skill, you get garbage in, garbage out. The advantage of these tools for me is that I can do a transient analysis faster.

Matties: Right. It's all about speed.

Ritchey: Yeah.

Matties: We were watching the AltiumLive presentation today, and the message was about speed, and also that the controls, the interface, is more intuitive as well.

Ritchey: Let me illustrate this. When we did the Amdahl machine, we had IBM 1130s, which are .1 MIP with 16k of memory. When they did a transient analysis in keypunch cards, I had a deck of those about an inch thick that I put in the machine. I waited about seven or eight hours and out the other end came another stack and a hand-plotted wave form. Well, all these things have done is make that happen faster, but that's what we had to work with. We still did the same thing with computers; it just took a long, long time and before we had computers we built test structures and measured them. That's why you see me with lots of test boards.

Matties: It seems to me that the wisdom of thousands of years of collective experience are embedded into these tools and that experience has to come across in not necessarily replacing the human interpretation or thinking, but certainly it gives you a point to start from that is by far more advanced that we've ever had.

Ritchey: What the tool does for you is error checking very quickly. You have to put the rules in and it's an exceedingly fast idiot that follows your rules really fast.

Matties: Let's change gears a little. You mentioned your course several times in the keynote. Tell me a little bit about your course, what people learn and what they can expect from it.

Ritchey: I mentioned earlier that most engineers are computer science majors and they don't have the fundamentals. That's where we start. We spend half a day on fundamentals, like what are fields and waves? What are transmission lines? What matters in a transmission line and then we go on from there, and when we are done, they've got all the tools and the information they need to go do a high-speed design. Power delivery engineering, which I mentioned is now the toughest part of design. Surprising how fast that happened and how quick we got to that. Two things happened: The day we started doing differential signaling replacing parallel busses the routing problem diminished dramatically, and because we have more transistors the power requirement shot up. Here's how easy differential pairs are. The terminators are inside the receivers, so all you have to do is put two wires on the board and go have a beer.

Matties: Sound like a good plan.

Ritchey: And they're self-timed. The clock is embedded in the data, so you don't even have to length-match two paths to each other. All that stuff that used to be really tough in laying out boards is real simple now. The flip side of that is power delivery has gotten painfully difficult. I think I mentioned that the latest design John Zasio and I did took two days to make all the SI rules, and over a month to get power delivery right. How's that for a flip?

Matties: What was the greatest challenge in that?

Ritchey: Well, you’ve got to make sure that every copper path from these high-current point of loads, 60 to 80 amp point of loads into the chip, has a low enough DC voltage drop that you don't get in trouble. The new one is 160 amps.

Matties: That's quite a load.

Ritchey: We think maybe we're going to go fishing. If we get that, we have a new problem. How do we get rid of the heat?

Matties: Well, that's the big issue now, isn't it? The thermal abatement.

Ritchey: Yeah, and this chip. To give you an idea of the heat density, if you turn an electric range on so that it's glowing red, that's the heat density on the chip. How do I keep that from going above 125°C? We use heat pipes, which is effectively water cooling, because you can't get rid of the heat with air and that's why I like that 3D bit that's in there. That lets me figure out how to fit my heat sinks in. I'm getting close to done.

Matties: So what are you going to do when you retire? I know you were in wines for quite a while and I think you've moved out of that.

Ritchey: I lost enough money in wine.

Matties: Sure, if you want to make a small fortune in wine, start with a large one.

Ritchey: We did exactly that. So John Zasio is my co-author, and he was my partner in the winery, and my son was the wine maker. And if you're an owner, you get the owner's free wine. When we liquidated, we did the math and we figured out our free wine was about $100 a bottle.

Matties: But it was tasty.

Ritchey: Oh, it was very good. So what am I going to do when I retire? I don't think I'm going to retire. I'm just kidding.

Matties: Just keep your teaching going.

Ritchey: Yes. My answer, and I said this to my kids, is that I’ll quit when the phone stops ringing. Both John and I retired once and it was real boring. Really, really boring. Part of the problem is everybody we liked to do things with was at work. And the real truth is, I don't think people really want to quit working. They just want to have a choice of when they work.

Matties: Buy their time back, exactly.

Ritchey: You pick and choose. I'm in the position when I can say, "No." And it doesn't cause me to miss my rent payment, and that's what you want to do, right?

Matties: It's great catching up with you. Is there anything that we haven't talked about that you feel like we should share with the industry?

Ritchey: I'll probably think of that half an hour from now when we're not talking.

Matties: Well, if you do, we'll just pick up where we left off. Otherwise, thank you very much Lee. It's always a pleasure to talk with you.

Ritchey: My pleasure too.

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