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THP210: Difference between THP210 & OPA1637?

Randy Rich
Prodigy 40 points

Part Number: THP210
Other Parts Discussed in Thread: OPA1637, OPA1632, OPA205, OPA206

I'm looking for an FDA for a couple applications. The THP210 or the OPA1637 looks promising at first glance. A few questions regarding what I've noticed so far:

  1. what are the differences between the THP210 & the OPA1637? They are both super-beta parts and almost all the specs -like noise, THD, GBW, etc., look virtually identical. The only difference I've noticed is better input offset voltage on the THP210. Are there any other differences I should be aware of?
  2. One of my applications has an extended frequency range (up to 300 kHz). I noticed the peak to peak output voltage swing drops off steeply above 100 kHz (Fig 6-18 in datasheet). Can you explain what is happening above 100 kHz? Can anything be done to improve this performance above 100 kHz? If not, can you recommend a similar FDA that would work up to 300 kHz? Are there any other specs I should be aware of above 100kHz? For example, how far up in frequency does the Vn flatband extend? The plot (FIG 6-8) only goes to 100 kHz. I presume it goes to 300 kHz or beyond, but would like to confirm.
  3. what is the history of the super-beta parts? Were they intially developed by Burr Brown and later became TI products or is the history something else? I don't need to know, so don't waste any time on this if you don't know. I'm just curious.
  • +1
    TI__Mastermind 27498 points

    Randy,

    1. You are correct that these devices are very similar.  The main difference is the DC performance (Vos and Vos drift).  The THP210 is optimized for precision DC applications so its offset is much lower than OPA1632 which is more intended for audio and other AC applications where Vos is not a concern.
    2. The curve shown in Figure 6-18 is sometimes called the "full-power bandwidth curve".  It is basically the point at which the sinusoidal waveform exceeds the slew rate limitation of the op amp.  Once this happens the sinusoidal waveform will become distorted.  It is important to note that this curve is specifically related to sine waves and not other wave shapes.  Basically when you are below the curve you should get minimal distortion due to slew-rate limitations, when you are above this curve the sinusoidal waveform at the output of the op amp will become distorted and look more like a triangle wave.  Op amp precision labs (slew rate section) covers this topic in detail.
    3. I do not believe Burr-Brown ever released a super beta device.  This is a relatively new development and we only have a few super beta devices released.  It is a good technology for bipolar bias current reduction so I think we will see more super beta parts in the future (super beta op amps OPA205, OPA206).

    I hope this helps.  Best regards, Art

  • 0 in reply to Art Kay
    Prodigy 40 points

    Thanks Art. Hadn't thought about slew rate. Makes sense now. 

    Best Regards, Randy