The Signal

  • We often receive applications questions relating to the power supply, input and output voltage range capabilities of our op amps. It can be confusing so here is an attempt to sort it out: First, common op amps don’t have ground terminals. A standard...
  • I posed a question a couple of weeks ago regarding film capacitors—what’s the meaning of the stripe on one end? Check the picture below. These are non-polarized capacitors so it’s not a polarity marking. A reader, Richard, answered...
  • Last week we looked at two very common reasons for oscillations or instability in op amp circuits. The ultimate cause of both was delay or phase shift in the feedback path. Review it here . I confess that I had intended to discuss cures for both circuits...
  • Bode plots are great analytical tools but you may not find them intuitive. This is a purely intuitive look at frequently encountered causes for op amp instability and oscillations. The perfectly damped response in figure 1 occurs with no delay in the...
  • Everyone knows that op amps should have power supply bypass capacitors located near the IC’s terminals, right? But why? Why, for example, is an amplifier more apt to oscillate without proper bypassing? The reasons will increase your understanding...
  • A holiday week is a good excuse to stray a bit off topic so this is my chance to tell you about Goop. It is by far the most versatile glue I’ve found. Okay, I promise to tie this in (though weakly) to electronics. Goop comes in a fat toothpaste...
  • It’s time for some fun! I’ve known a few folks who have tormented colleagues with a resistor cube—equal resistors on all sides. So in case you’ve solved that one, let’s add a twist. In this cube, not all the resistors are...
  • We get many questions on our forums about designing current sources of all types—constant currents, voltage-controlled currents, AC currents, high currents, low currents, active current sources and passive current sinks. All different kinds. A single...
  • Have you noticed?...it’s rare to find new generation op amps and other ICs in DIPs (dual-inline packages). Without volume demand, it’s not economically viable to offer new ICs in DIPs. Breadboarding with these newer fine-pitch micro-packages...
  • Is it possible to parallel two op amps to get twice the output current? We get this question periodically on our E2E forums. Though we may answer with a qualified “yes,” it tends to make us shudder just a bit. It can be done… but...