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I have the following bode plot and I am trying to determine the DC-Gain and the Gain at high frequenciesenter image description here

How do I calculate the DC-Gain from this plot? Matlab's function dcgain() says that it is equal to 2. How do determine this?

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  • \$\begingroup\$ If the gain, in terms of output signal magnitude divided by input signal magnitude, is \$G\$ then the gain in dB is \$20log_{10} G\$ \$\endgroup\$ – Chu Apr 6 '17 at 19:04
  • \$\begingroup\$ From the graph 6dB----> 6/20 = 0.3;---->10^0.3 = 2[V/V] \$\endgroup\$ – G36 Apr 6 '17 at 19:06
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Gain(dB) = 20 x log(amplitude Gain)

amplitude Gain = 10 ^ (Gain(dB)/20)

In your case it is 6dB -> amplitude Gain of ~2

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  • \$\begingroup\$ This assumes the Bode plot captures all the important behavior and there isn't some low frequency pole or zero at a frequency lower than the left edge of the graph. \$\endgroup\$ – The Photon Apr 6 '17 at 19:19
  • \$\begingroup\$ If there was a pole at lower frequency, the phase could not be zero. The only scenario where the DC gain would be different would be because of a combination of a pole AND a zero at lower frequency, not because of a single pole. \$\endgroup\$ – Claudio Avi Chami Apr 7 '17 at 5:06

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