The Magic Of A Diode Sampler To Increase Oscilloscope Bandwidth
Making an oscilloscope is relatively easy, while making a very fast oscilloscope is hard. Thereās a trick that converts a mundane instrument into a very fast one, itās been around since the 1950s, and [CuriousMarc] has a video explaining it with an instrument from the 1960s . The diode sampler is the electronic equivalent of a stroboscope, capturing parts of multiple cycle of a waveform to give a much-slowed-down representation of it on the screen. How it works is both extremely simple, and also exceptionally clever as some genius-level high-speed tricks are used to push it to the limit. Weāve put the video below the break. [Marc] has a Keysight 100 MHz āscope and the sampler allows him to use it to show 4 GHz. Inside the instrument is a pair of sample-and-hold circuits using fast diodes as RF switches, triggered by very low-rise-time short pulses. Clever tricks abound, such as using the diode pair to cancel out pulse leakage finding its way back to the source. To complete this black...