Figure 1B: The Bode plot for a first-order (one-pole) lowpass filter the straight-line approximations are labeled "Bode pole" phase is 90° lower than for Figure 1A because the phase contribution of the numerator is 0° at all frequencies. JSTOR ( December 2011) ( Learn how and when to remove this template message)įigure 1A: The Bode plot for a first-order (one-pole) highpass filter the straight-line approximations are labeled "Bode pole" phase varies from 90° at low frequencies (due to the contribution of the numerator, which is 90° at all frequencies) to 0° at high frequencies (where the phase contribution of the denominator is −90° and cancels the contribution of the numerator).Unsourced material may be challenged and removed.
Please help improve this article by adding citations to reliable sources. (There's a step-by-step tutorial on how to get input and output impedances here.This article needs additional citations for verification. The output impedance is about \$800 \ \Omega\$. If you run this simulation, you'll get this plot for output impedance: And then we'll plot MAG(V(I1.nA)/I(I1.nA)) to see the output impedance: We'll set this current source to have 0 current at DC so that it's only being used as a small-signal current source, pushing and pulling current from the output node. In this case, by mousing over the plot, you'll find that it's about \$2 \ \text\Omega\$ in the pass band:įor output impedance, we need to modify the circuit slightly, just by adding a test current source connected to the output. Input impedance is easy: we can just take the same circuit above and instead plot the expression MAG(V(V1.nA)/I(V1.nA)), which looks at the small-signal current relative to the small-signal voltage on source V1 and plots their ratio, an impedance. (If you need to recreate this on your own, there's a step-by-step tutorial on how to draw a circuit and get the voltage gain Bode Plot here.) Input Impedance If you open the circuit above and run the simulation, you'll get the following Bode Plot showing approximately +30 dB of gain in the pass band: Simulate this circuit – Schematic created using CircuitLab I've quickly drawn your circuit and set it up to get the Bode plot of voltage gain, setting up a frequency domain simulation with V1 as the source and DB(MAG(V(out))) and PHDEG(V(out)) as the plot outputs: I don't use Multisim, but it's easy to find an amplifier's voltage gain and input and output impedances with the CircuitLab circuit simulator.
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