NF FRA51602, Instruction Manual

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4.2 Simple operation for the first use
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FRA 51602
6) In the same way, turn the knob to find the frequency at which the phase is closest to 0°. The gain at that
frequency is the gain margin. Because the frequency is relatively high, it may be difficult to clearly read
the gain margin because of noise, etc. for some circuits. In that case, it is possible to evaluate the loop
stability by using the phase margin alone.
As was explained in the most general example for measuring a DC-DC converter, change the measurement
frequency range, oscillator amplitude, and number of integration rounds as is appropriate for the
characteristics of the circuit being measured.
Set the DC bias of the instrument oscillator to 0 V. Regardless of the output voltage of the circuit being
measured, it is not necessary to set the DC bias when measuring loop gain.