Teledyne LeCroy DA1855A - Manual (Page 34)

DA1855A Differential Amplifier
28 922258-00 Rev A
the centerline. Following are a few observations on using the DA1855A comparison voltage mode
(V
COMP
):
• The negative input and its AC, OFF and DC coupling are disabled. Instead of being a
differential amplifier, the DA1855A becomes a differential comparator. It compares the
voltage present at the +INPUT with the output of the Precision Voltage Generator and when
they are equal, the output of the DA1855A is zero volts.
• The value displayed by the Precision Voltage Generator indicates a waveform’s voltage, with
respect to ground, as it passes through the oscilloscope display’s centerline. By using the
DA1855A in the comparison voltage mode and the oscilloscope in a high sensitivity setting,
highly accurate voltage measurements can be made.
Differential Offset Operation (V
DIFF
)
Set the DA1855A up as follows through the oscilloscope user interface:
PVG Mode V
COMP
+Coupling DC
DA1855A (Atten/Gain) Manual
List Select: Upper BWL FULL BWL
List Select: Gain X10
List Select: Atten ÷1
List Select Input R 1 M Ω
Leaving the OFFSET control set as in the previous example, the DA1855A front panel indicators
should be lit as follows:
+INPUT DC
–INPUT V
COMP
BW LIMIT FULL
GAIN X10
ATTENUATOR ч ч1
INPUT RESISTANCE 1 M Ω
PVG +0.0500
COMPARISON or
DIFFERENTIAL
COMPARISON
EFFECTIVE GAIN X10