Chopper Op Amps—are they really noisy?


Chopper op amps offer very low offset voltage and dramatically reduce low frequency 1/f (flicker) noise. How do they do it? Here’s a quick-read on the tricks.

Click Here to read on EDN Magazine site.

  • Bruce-san, I am a little confused about technical term "Chopper" because TLC2654 seems "Chopper" by its datasheet, however, it looks "auto-zero". Which is true ?

  • Ori-san— Agreed, the diagram of the 25-year-old TLC2654 shows what we would now call an auto-zero-type topology. This technique periodically shorts the input of a correction amplifier, storing its output offset on capacitors (external capacitors, in this case), then subtracts the offset from the active signal path in the next cycle of the clock. The term “chopper” has been used somewhat casually through the years to describe a variety of clocked zeroing techniques. It’s not entirely clear whether the author of this old data sheet made a mistake, or perhaps the terminology has gained greater clarity over the years.  — Bruce

  • Mr. trump, is TI or BB offering any integrated chopper op amps you mentioned?  Not the auto-zero ones like TLC2652 or TLC2654.Thank you!

  • He--  Op amps from TI that use the technology discussed in this blog include OPA333, OPA330, OPA378 and OPA188. These products also have dual versions that are shown on the same data sheet as the single version.  --  Bruce