NF ZM2371, Instruction Manual

Page: 18 / 255

1.4 Principle of Operation
1-5 ZM2371/ZM2372

Oscillator
The oscillator generates sine-wave signals having exact frequencies by means of a direct
digital frequency synthetic method based on the reference clock of crystal oscillator.
When the Automatic Level Control (ALC) function is effective, the main processor adjusts
automatically the signal level so that the voltage and current monitored values become the
specified values.

Impedance Bridge
The current flowing in the DUT is converted into the voltage by the range resistance and
differential amplifier. At this time, the potential between L
CUR
and L
POT
terminals is
maintained to almost zero by automatic balancing motion of the bridge. Accordingly, the
current that runs away to the ground through capacitance to earth and insulation resistance
and is not detected can be reduced.
The voltage applied to the DUT is detected by the differential amplifier.
After that, the voltage signal and current signal are converted into digital values by the A/D
converter, and sent to the main processor.