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THS6222: THS6222 or THS6012 for minimum-distortion 0 - 300kHz @ 32V Vcc 200Rload

Pavel Hofman1
Prodigy 170 points
Part Number: THS6222
Other Parts Discussed in Thread: THS6012, THS6022, BUF634A, LME49724, TINA-TI, THS4151, THS4150, THS4552

Hi, I am looking for a balanced output amplifier of a signal generator 0 - 300kHz, Vcc +/-16V, output total Rload 200R (between + and - output), Vout +/-14Vmax (+/-56Vpp), gain 3-4V/V, mostly resistive load. The most likely circuit would be composite with an appropriate signal opamp at the front. The main performance criteria are THD+N and IMD.

Please which of your high-speed high-power opamps would you recommend? Could THS6222 offer lower THD+N/IMD than the older THS6012?

THS6222 datasheet shows a huge increase in IMD for frequencies  below 1MHz. Is that the case with THS6012 too? Is there a way to avoid the IMD increase in THS6222 using the composite connection with another high-gain front opamp? TPA6120 (sibling of THS6012 IIUC) componsite circuits feature very low IMDs at <1MHz.

THS6222 datasheet HD2/3 charts start at 1MHz. The gain charts start at 5V/V, is the device stable at gain 3-4V/V? According to the datasheet TPA6120 allows gain 1V/V.

Thank you very much for your help.

Best regards,

Pavel.

  • 0
    TI__Mastermind 22250 points

    Hello Pavel,

      Thank you for providing all this information. The THS6012 will follow this same trend as the THS6022 for IMD vs THD, but THS6222 has better distortion performance compared to THS6012. If you are looking for a differential output meeting the specs you have listed, but at the lowest distortion; depending on your application (if not PLC line driver), how about an audio amplifier with high output FDA or buffer in a composite configuration? I have linked collateral we have on this here. The DC performance will follow the first amplifier, but the second amplifier will provide the output current capabilities for +/-14V max over 200Ohm load. 

      LME49724 is an ultra low distortion device which is able to support +/-14V at +/-16V Vcc with enough slew rate to support a 200kHz sin wave signal. The BUF634A has enough output current at a high voltage supply to support your requirements. I drafted a quick example of this setup which I have attached below (Tina-TI file). 

      We also have THS4150/THS4151 which has slightly better distortion performance requirements to the THS6222 at the lower frequencies. But, not enough output current, so would need a second stage here as well.

    Composite_LowDistortion.tsc

    Thank you,

    Sima  

  • 0 in reply to SimaJalaleddine
    Guru 47395 points

    Morning Sima, 

    That LME49724 schematic looks pretty good, that part is an audio FDA done by the National guys where that whole LME line is pretty remarkable, Somehow - the landing page got changed to a 2-channel name? hardly, this is a single FDA with differential outputs - There are dual channel FDA's like the THS4552, but this is not one of them. 

  • 0 in reply to Michael Steffes
    TI__Mastermind 22250 points

    Morning Michael,

       That is a good point. It incorrectly refers to this part as a 2-channel part in the header, but lists the correct number of channels. I will let the team that covers this device know.

    Thank you,

    Sima 

  • 0 in reply to SimaJalaleddine
    Prodigy 170 points

    Hi Sima, thanks a lot for your examples and hints. I will look at your suggestions.

    With regards,

    Pavel.