Summary: <p>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 <a href="https://eestalktech.com">electrical engineering podcast</a>.</p> <div class="jetpack-video-wrapper"></div> <audio class="wp-audio-shortcode" id="audio-1646-16" style="width: 100%;"><a href="https://eestalktech.com/wp-content/uploads/2017/10/power-integrity-and-signal-integrity-ees-talk-tech-electrical-engineering-podcast.mp3">https://eestalktech.com/wp-content/uploads/2017/10/power-integrity-and-signal-integrity-ees-talk-tech-electrical-engineering-podcast.mp3</a></audio> <p>00:15 Kenny gave us a tip during <a href="http://www.scopemonth.com">scope month</a></p> <p>01:26 There are two types of power people.</p> <p>There are power producers, like the wind farms, power plants, and AC/DC adapter creators</p> <p>There are power consumers, who care very much about their power quality. The <a href="https://www.youtube.com/watch?v=eVB_n4t57Yc">ripple on power supplies</a>, etc.</p> <p>3:03 <a href="http://literature.cdn.keysight.com/litweb/pdf/5992-0493EN.pdf">Power integrity</a> is the study of the effectiveness of the conversion and delivery of DC power from the source to the gates on the IC.</p> <p>3:45 If <a href="http://eestalktech.com/2017/04/26/artificial-intelligence-and-dispersed-computing/">Moore’s Law</a> holds out for another 600 years, we will have a computer that is capable of simulating every atom in the known universe.</p> <p>4:35 Thermal hotspots were causing problems, so voltage levels started dropping</p> <p>5:00 Kenny went to Amazon to look for a power integrity book. There were only 2-3 books a few years ago</p> <p>Power integrity has been a thing since the 1930s</p> <p>5:50 Product functional reliability is directly proportional to the power quality in a product.</p> <p>We’re supplying a voltage to devices, but also current. So, this starts to look a lot like Ohm’s law.</p> <p>A device has both power and a ground plane.</p> <p>Power integrity pioneers include Istvan Novak and Ray Ridley and they talk about flat impedance power planes.</p> <p>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.</p> <p>If you can maintain a frequency flat impedance, you don’t see noise on your power supplies.</p> <p>7:55 Think back to <a href="https://www.youtube.com/watch?v=heufatGyL1s">circuits 101</a>, an <a href="https://www.youtube.com/watch?v=btv0uRi3xJ0">inductor</a> 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.</p> <p>8:40 When you look at boards, you see bypass capacitors to counteract the inductors</p> <p>10:30 Experienced engineers use a lot of intuition when working out power distribution. Now, there’s a lot of localized power distribution.</p> <p>11:15 A typical SSD has 12 power supplies</p> <p>A tablet can have 50 power supplies</p> <p>Some of our <a href="http://www.keysight.com/en/pcx-x2015004/oscilloscopes?cc=US">oscilloscopes</a> have 180 power supply rails</p> <p>Next generation mobile electronics 100-200 power supplies</p> <p>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.</p> <p>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 </p>
