LT1167 in LTSpice

Hi

I tried to build EMG sensor based on LT1167. I found typical application (figure 8) and try simulate it in LTSPICE.

AC Analysis looks ok but something weird happen in trans.

After first filter (Highpass - red wave) it looks ok but after second filter it gives me square wave. Why this is happened? Is suppose to just gain in this frequency. Maybe I don't understand what going on in circuit.

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  • Hi Kil307,

    You may be seeing the output stage gain causing the output saturating and running into the rails.

    There is a large gain (1+ 10k/100 = 101 V/V). I cannot see your attached vertical scale. The point is if the signal is large enough after the high pass filter (C1, R4), U2 (running off of +/-3V supplies) will limit the output swing.

    Can you reduce the input signal, or the gain (reduce R5) to see if the problem goes away?

    Regards,

    Hooman

Reply
  • Hi Kil307,

    You may be seeing the output stage gain causing the output saturating and running into the rails.

    There is a large gain (1+ 10k/100 = 101 V/V). I cannot see your attached vertical scale. The point is if the signal is large enough after the high pass filter (C1, R4), U2 (running off of +/-3V supplies) will limit the output swing.

    Can you reduce the input signal, or the gain (reduce R5) to see if the problem goes away?

    Regards,

    Hooman

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