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TLV3541: Support Config Diff to Single For TLV3541

Alone173
Expert 1325 points
Part Number: TLV3541

Tool/software:

Hello everyone.

I need build a board to convert the diff to single end signal with ( BW~0.2GHZ, unity gain).
I choose op-amp TLV3541 and make the simulation on TINA,

The config with gain =1, input signal from 2Vpp, 0-200MHZ.

But with the input signal larger than 50MHZ, the gain is reduce.

Please help to show the issue on the current config.

Thank you.

  • 0
    TI__Intellectual 2600 points

    Hi Alone,

    There are multiple reason why this may not work:-

    1. The unity gain bandwidth of 200Mhz is for small signal input. In your case the input is a large signal of 2Vpp and for this the bandwidth is much less.

    2. For bandwidth calculation you should consider the noise gain and not the signal gain. Here the noise gain here is 2V/V (signal gain is 1V/V). So for small signal also your bandwidth will be 90Mhz and not 200Mhz. So the gain will start rolling off one decade before 90Mhz and at 50Mhz it will already be around -0.75dB 

    2. The output in your case is slew rate limited and so will get distorted. You can refer to the Figure 17 of the datasheet where it show for large output swing what is the maximum input frequency signal you can give without causing any slew rate induced distortion at any particular output voltage. For 2Vpp you can maximum go upto ~12Mhz without any distortion.

    3. It is recommened to bias the input at mid supply. Presently it is baised at VEE=0V, so your signal will get clamped from one side. For vdd of 3.3V, you need to tie the other side of the R4 resistor to 1.65V .

    Regards

    Anant