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We have this circuit enter image description here

And using the simulator I found the load voltage at the resistor 10 k ohm, based on different frequencies. And I got this curve at the Bode plot. where Y axis represents the voltage across the load ( resistor 10 k ohm in the picture) and x axis the frequency. enter image description here

Using this plot I have to predict the Vout at frequency 10 k Hertz. I know that the output voltage should be reduced by a factor of 104( 80 dB), so the output voltage would be 250 uV.

But I am not sure I fully understand why we should use this factor, and how we used it to get the result 250uV.

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  • \$\begingroup\$ Reduced by a factor of 104 means a gain of approximately -40dB. \$\endgroup\$
    – Chu
    Commented Apr 23, 2020 at 21:41

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I’m assuming you meant that you use a 10k ohm load and want to know the Vout when input frequency is 10khz. Assuming this is the gain of the circuit plotted on the y-axis. You would look at the bode plot and pin point the 10khz frequency point on horizontal axis. Draw a vertical line at this point. Then find on the curve where This vertical line intersects the curve. At this point Vout=Vin*gain.

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  • \$\begingroup\$ I should have mentioned that the y axis is the voltage across the load \$\endgroup\$
    – Kasiopea
    Commented Apr 23, 2020 at 18:43
  • \$\begingroup\$ Well in that case you would just see where the vertical line passes through curve and then you have Vout. Though let me ask, can you see the curve at 10khz? \$\endgroup\$
    – Leoman12
    Commented Apr 23, 2020 at 18:46
  • \$\begingroup\$ Reason I ask is because it looks like the curve only goes down to like 5khz \$\endgroup\$
    – Leoman12
    Commented Apr 23, 2020 at 18:47
  • \$\begingroup\$ No, I cannot thats why I was confused \$\endgroup\$
    – Kasiopea
    Commented Apr 23, 2020 at 18:52
  • \$\begingroup\$ So I got that curve by measuring the voltage at the Resistor Ri1. Is that the right resistor that I should have measure the voltage drop? \$\endgroup\$
    – Kasiopea
    Commented Apr 23, 2020 at 18:54

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