LeCroy DA1855A Operation page 6

DA1855A Differential Amplifier
Precision Voltage Generator
3-6
Note that while in V
COMP
single ended measurements. The –INPUT connector is not
usable when V is selected. The input signal applied to the +
COMP
INPUT is referenced to ground offset by the value set by the
Precision Voltage Generator. Large calibrated offsets can be
obtained while making differential measurements by using V
mode.
The PVG generates the voltage which is used in the V
V modes and appears at the rear panel OFFSET VOLTAGE
DIFF
(PVG) output connector for use as a reference voltage.
The Precision Voltage Generator (PVG) output range is
Volt. The PVG is never attenuated by the input attenuator.
Attenuation of the +INPUT signal by the 10 input attenuator will
cause the PVG to null out an input voltage up to
which is ten times larger than the actual PVG voltage.
The increase in common mode voltage range also applies when
using attenuating probes.
When the DA1855A is used with attenuating probes that feature
readout, the PVG display is changed to indicate the voltage at the
+INPUT probe tip which will bring the amplifier output to zero.
When connected to a LeCroy oscilloscope via the ProBus
interface, the oscilloscope OFFSET control increments or
decrements the PVG's output voltage and the offset value will be
shown on the six PVG front panel indicators. The new offset
value will also be displayed on the oscilloscope's screen for a few
seconds after a change has been made.
When connected to an oscilloscope not provided with a ProBus
interface, the PVG can be accessed by means of push buttons.
Above each digit is a push button which increments the
corresponding digit by one when pushed. When held, the digit
continues to increment, eventually incrementing the next higher
digit.
Similarly, below each digit is a push button which decrements the
corresponding digit.
The button above the left-most digit changes the PVG output
polarity. The ZERO button below the left-most digit sets the
output to zero and invokes the PVG's Auto Zero function.
ISSUED: July 2002
mode, the amplifier is configured for
DIFF
and
COMP
15.500
155.00 Volt
DA1855A-OM-E Rev A