Analog is the bane of electrical engineering students and conjures up bad flashbacks of analyzing useless circuit diagrams composed of passive components in bizarre configurations and trying to remember equivalent circuits for different types of transistor signal analysis for me. It’s even worse for non-electrical engineering students because analog is a mysterious form of black magic that only bearded old men understand. Incidentally, all of those flashbacks were eliminated after I discovered two magical tools: SPICE simulation and Matlab.
It’s no wonder that analog has taken a backseat over the past many years as breakthrough after breakthrough in digital technology kept inundating us, showering us with cheap hardware, free software, and boatloads of information. But a peculiar trend seems to be emerging with the increasing tech savvy of everyday users combined with the mountains of information that are now available at everyone’s fingertips. That, along with the recent popularity of DIY hardware, hardware hacking, circuit bending, electronic art installations, and environmental sensing, are starting to spur curiosity in how technology can fit into our everyday world. All of a sudden analog electronics is back in vogue again and it seems to be coming from a culmination of multiple factors.
Two of the main factors affecting a renewal of interest in analog electronics is power supplies and sensors. Power supplies, once an afterthought in the design of an electronic circuit has risen to the forefront of product requirements. With people handling more and more portable electronics, low power consumption, efficiency, and recharging are becoming things that tech enthusiasts are extremely concerned about. An off-the-shelf device may be using a cheap but inefficient power supply circuit that might not necessarily operate until a battery is completely drained. Or some people might be interested in adding solar recharging capability to their devices. This is leading to a large interest in products like the Adafruit Minty Boost kit which is actually Adafruit's bestselling product and is a portable recharging circuit for battery operated electronic devices. Battery monitoring, recharging, energy harvesting, power distribution, AC/DC and DC/DC conversion are now things that not only concern cell phone designers but everyday tech artists, hackers, and electronics enthusiasts. In fact, one of the people from Tokyo Hackerspace, who just recently learned how to solder, is now designing his own 6 A-hr solar rechargeable Lithium-polymer battery-based portable power supply. His day job is an IT admin and web programmer. I was fascinated.
I’m also intrigued by the really interesting analog devices that are coming out recently like the LT3108 DC/DC energy harvesting boost converter which can convert a power source as low as 20mV to a usable voltage of 3.3V. It’s what researchers are using to power their circuits off of tree sap! Another interesting device is a battery monitor capable of monitoring voltage on a string of 12 separate Lithium-Polymer battery cells . The applications listed are “portable equipment” and “electric vehicles”, a fairly diverse combination. And just this morning, EETimes reported that major semiconductor companies are reporting shortages for their analog product lines .
But enough about power supplies, if you start getting into things like sensors, then you get really deep into the pile. There’s a recent trend in tech circles for interfacing the online/virtual world of the internet with the physical/real world of, well…the real world. This means that people are designing web and PC interfaces that connect to devices with sensors inside them that actually measure physical attributes and display them online or at least on a computer. A simple example would be the Nintendo Wii which uses accelerometers and gyroscopes to send position data to its central unit which translates that into movement inside its games. There’s also the integration of more and more sensors into devices that we carry around on an everyday basis like cell phones. A typical iPhone has an accelerometer, capacitive touch, ambient light, and proximity sensors.
This exposure to sensors in everyday objects has gotten a lot of (not necessarily engineering) people interested in integrating sensors into their designs as well, and you can see them in hacker projects, art-installations, and even *gasp* open source projects. However you can only go so far with sensors before you realize that you’re going to need to get your hands dirty and start playing with analog circuits. Typical things you see in sensor circuits are wheatstone bridges, monostable multivibrators (555s), frequency/voltage converters, analog filters, and a dizzying array of op-amps.
Op-amps, in general, are super duper interesting and volumes of books and application notes have been written on them. They’re the workhorse of the analog industry and just as there’s an app for any iPhone need, there’s usually an op-amp or op-amp circuit for any analog need. There are general purpose op-amps, instrumentation amplifiers, programmable gain amplifiers, logarithmic amplifiers, and the list goes on. Within op-amps, there are bipolar junction transistor-based, FET-based, JFET-based, CMOS-based, rail-to-rail, single supply, low offset voltage, low noise, etc, etc, etc… I wouldn’t be surprised if books like Horowitz and Hill’s “Art of Electronics” or “Op Amp Applications Handbook” by Walt Jung and other staff at Analog Devices start increasing in Amazon sales rank soon.
And then there’s wireless sensor networks. There has been an unbelievable amount of interest in wireless sensor networks in the past few years and, in my opinion, WSNs are probably one of the craziest multi-disciplinary fields to be in right now. On the analog side, you have to deal with extremely low power consumption requirements, battery recharging, energy harvesting circuits, wireless communication, and figuring out how to interface a huge array of sensors to a microcontroller. On the digital side, you have to grapple with extremely constrained memory, endless drivers, protocol stacks, security, and actual applications that run on top of all that. All-in-all, it makes for some really fun times, and those deep in the WSN community are probably some of the most bizarre, masochistic, and smartest people I’ve ever met.
Analog electronics seems to be seeing a renewed interest in both electronics and electronics enthusiast circles, but it’s mistaken to think that it’s the simple old Heath kit type of analog electronics from yesteryear. Today’s analog electronics isn’t just about resistors and op-amps, but instead requires understanding the complete system of internet technologies, PC interfacing, and embedded programming, on top of the actual analog circuit knowledge. In other words, the amount of information available today is exponentially greater, but the amount of information required to integrate it is also exponentially greater. In my opinion, analog is indeed making a comeback, but be careful…it’s not your grandfather’s analog…