Electronics is Fun

With the availability of many modern instrumentation amplifiers today, it has become quite an easy task to build a very precise current source. Current source is an important electronic building block that is supposed to deliver a constant defined current regardless of the load. If to a voltage source the low output impedance is the important characteristic, high output impedance would be for the current source. High output impedance means that as the load voltage changes due to current being sourced or sunk, there is very small change to the current. Ideally we would want the current to remain unchanged, because it is what it is supposed to do, to be a constant current source. My Digilent Discovery Kit includes an AD8226 in-amp, and together with a buffer, OP02 , also included in the kit, I made a very simple but very precise current source.  What I like about this in-amp is it is a low-power, wide input and supply range instrumentation amplifier at +/-1.35 to +/18V, ve...

by DarwinT Well I've been taught in school only one thing about the bandwidth of an op amp, or perhaps it just didn't register enough in my brain that there's another kind of bandwidth, and all of a sudden I hear this large signal bandwidth, or sometimes referred to as the full-power bandwidth, about op amps. At first I thought that this "large signal bandwidth" thing should be pretty obvious and a no-brainer, until I got confused some and I realize it can't be ignored anymore. That I already know, and I wanted to know more about it. How come nobody explained this thing to me! When you look at an op amp's datasheet (e.g. ADA4895-1 ), the manufacturer often publish the bandwidth on the front page, otherwise it can always be found in the collections of plots inside. It's basically the unity gain frequency of the open loop gain of the amplifier. What is not so obvious is that this doesn't apply to all level of signals you intend to use your amp...