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Differences between OPA655 and OPA656

Other Parts Discussed in Thread: OPA656, OPA657

I was thinking about using an old design I had (a high gain, high speed transimpedance preamp for an IR photodiode) that used an OPA655.  But that part now appears obsolete, replaced by the OPA656.  Can you get me the details on the differences?

  • ajp,

    The OPA656 was designed to be a replacement for our earlier OPA655, to provide similar bandwidth and slew rate with significantly lower quiescent current and DC errors. Most applications for the OPA655 can consider the OPA656 as a drop in alternative (SO-8 only). Specifications are either similar or improved except distortion, where the OPA655 had 90dBc SFDR at 5MHz and OPA656 is 74dBc. This is probably not a large concern for transimpedance amplifier (TIA) applications.

    While the OPA656 is unity gain stable, a companion part, the OPA657, is a non-unity gain stable JFET input amplifier that provides much higher gain bandwidth. The JFET input stage for both parts provides exceptionally low input bias current and is trimmed for both low offset voltage and temperature drift. The low Vio drift on the OPA656 and OPA657 is a tested parameter. This gives a standard grade (+/-12uV/C drift test limit) and a high grade version (+/-6uV/C drift test limit). Typical input offset voltage and drift will be < +/-0.1mV and +/-2uV/C for the high grade of both the OPA656 and OPA657.  

  • Thank you; this helps me to understand.