Summary: <p> </p> <p>We talk to ASIC Planner Mike Beyers about what it takes to design the world’s fastest ADC in today’s electrical engineering podcast.</p> <p>Video Version (YouTube):</p> <p> </p> <div class="jetpack-video-wrapper"></div> <p>Audio Only:</p> <audio class="wp-audio-shortcode" id="audio-880-22" style="width: 100%;"><a href="https://eestalktech.com/wp-content/uploads/2017/07/the-worlds-fastest-adc.mp3">https://eestalktech.com/wp-content/uploads/2017/07/the-worlds-fastest-adc.mp3</a></audio> <p>Intro:<br> Mike is an <a href="http://eestalktech.com/2017/05/25/all-about-asics/">ASIC</a> planner on the ASIC Design Team.</p> <p>Prestudy, <a href="https://community.keysight.com/community/keysight-blogs/oscilloscopes/blog/2017/05/15/creating-an-asic-our-quest-to-make-the-best-cheap-oscilloscope">learn about making an ASIC</a>.</p> <p>00:30</p> <p>What is an ADC?</p> <p>An ADC is an analog to digital converter, it takes analog data inputs and provides digital data outputs.</p> <p>What’s the difference between analog and digital ASICs?</p> <p>1:00<br> There are three types of ASICs:<br> 1.Signal conditioning ASICs<br> 2. Between 1 and 3 is a converter, either digital to analog (DAC) or analog to digital (ADC)<br> 3. Signal processing ASICs, also known as digital ASICs</p> <p>1:50<br> Signal conditioning ASICs can be very simple or very complicated<br> e.g. Stripline filters are simple, front end of an <a href="http://www.keysight.com/en/pcx-x2015004/oscilloscopes?cc=US&lc=eng">oscilloscope</a> can be complicated</p> <p>2:45<br> There’s a distinction between a converter vs. an analog chip with some digital functionality<br> A converter has both digital and analog. But there are some analog chips with a digital interface, like an I2C or SPI interface.</p> <p>4:25<br> How do you get what’s happening into the analog world onto a digital interface, and how fast can you do it?</p> <p>4:35<br> Mike Hoffman designed a basic ADC design in school using a chain of <a href="https://en.wikipedia.org/wiki/Operational_amplifier">operational amplifiers</a> (opamps)<br> A ladder converter, or “thermometer code” is the most basic of ADC designs</p> <p>6:00<br> A slow ADC can use single ended CMOS, a faster ADC might use parallel LVDS, now it’s almost always <a href="https://en.wikipedia.org/wiki/SerDes">SERDES </a>for highest performance chips</p> <p>6:35<br> The world’s fastest ADC?</p> <p>6:55<br> Why do we <a href="https://www.youtube.com/playlist?list=PLzHyxysSubUmxGOMVpiKLxouweh2AAlG1">design ADCs</a>? We usually don’t make what we can buy off the shelf.</p> <p>The Nyquist rate determines the necessary sample rate, for example, a 10 GHz signal needs to be sampled at 20 – 25 Gigasamples per second<br> 1/25 GHz = 40 ps</p> <p>8:45<br> ADC Vertical resolution, or the number of bits.</p> <p>So, ADCs generally have two main specs, speed (sample rate) and vertical resolution.</p> <p>9:00<br> The ability to measure time very accurately is often most important, but people often miss the <a href="http://literature.cdn.keysight.com/litweb/pdf/5989-3020EN.pdf">noise</a> side of things.</p> <p>9:45<br> It’s easy to oversimplify into just two specs. But, there’s more that hast to be considered. Specifications like bandwidth, frequency flatness, noise, and SFDR</p> <p>10:20<br> It’s much easier to add bits to an ADC design than it is to decrease the ADCs noise.</p> <p>10:42<br> Noise floor, SFDR, and SNR measure how good an analog to digital converter is.</p> <p>SFDR means “spurious free dynamic range” and <a href="https://community.keysight.com/community/keysight-blogs/oscilloscopes/blog/2017/01/04/how-to-extend-snr-in-wideband-oscilloscope-based-pulsed-rf"></a></p>
