Chapter 7
AC Analysis

m7.4 Phasor-Domain Analysis Techniques

The circuit of Figure m7.4 operates at 1 kHz. Determine node voltages V_A and V_B. Component values are: R₁ = 4.7 kΩ, R₂ = 3.3 kΩ, R₃ = 2.2 kΩ, C₁ = 0.047 μF, C₂ = 0.1 μF, V₁ = 90^∘ V and V₂ = 3- 90^∘ V.

NI Multisim Measurements

Enter the circuit of Figure m7.4 and run an AC analysis to measure the voltage magnitude and phase of V_A and V_B.

More specifically:

• Use the AC_VOLTAGE source. Set the “AC Analysis Magnitude” and “AC Analysis Phase” values according to the specified voltage source values.
• Set up an Simulate → Analyses → AC Analysis to sweep the frequency over a range that includes 1 kHz; use a “Linear” sweep type with “Vertical Scale” set to “Linear.”
• Use the “Grapher View” cursors to measure the voltage magnitude and phase at 1 kHz.

NI myDAQ Measurements

Construct the circuit of Figure m7.4. Use the NI ELVISmx Arbitrary Waveform Generator to create the sinusoidal voltage sources; use AO0 to create V₁ and AO1 to create V₂. Use the NI ELVISmx Oscilloscope to measure the node voltages V_A and V_B. Take V₁ as the reference voltage when measuring phase.

Additional helpful tips:

• Set the Arbitrary Waveform Generator sampling rate to its maximum value of 200 kHz.
• Create a single period of a unit-amplitude 1 kHz sinusoid for each output channel. Adjust the phase of the AO1 channel to match the phase of V₂.
• Set the “Gain” controls of the Arbitrary Waveform Generator to match the magnitudes of the specified voltage sources.
• Refer to Appendix F to learn how to use the oscilloscope to measure magnitude and phase.