LeCroy DA1855A Operation page 8

DA1855A Differential Amplifier
Effective Gain
BW Limit
3-8
offset provides much greater range than the conventional position
control. For example, at 50 mV/div, the V
200 divisions of range.
Operation of the DA1855A using the V
as V except for the following:
COMP
• The –INPUT remains active, allowing full use of the
DA1855A as a differential amplifier.
• The maximum range of the PVG is 10.000 Volt in X1
GAIN and 1.0000 Volt in X10 GAIN. The effects of the 10
input ATTENUATOR and probe attenuation are the same
as when using V
the effective offset.
The DA1855A's PVG display is changed to indicate the voltage
that, if applied between the +INPUT and –INPUT, would bring the
amplifier output to zero. When the DA1855A is used with
attenuating probes which feature readout, the PVG display is
scaled to include the effect of probe attenuation.
Six indicators (LEDs) across the top of the DA1855A front panel
show the total gain from the instrument input to output. Logic
within the amplifier includes the gain, internal attenuation, and
probe attenuation factors (when readout encoded probes are
used) to determine the effective gain. When the X1 light is ON,
the overall amplifier voltage gain (amplification) is unity. Similarly,
X10 indicates an overall amplification of ten times. 10 Indicates
the voltage amplification is 0.1, and so forth.
The DA1855A communicates the effective gain information to the
LeCroy oscilloscope when the ProBus interface is used. This
corrects the scale factor of the displayed waveforms, cursors and
measurements.
When LeCroy DXC series or other readout encoded probes are
used, the effective gain includes the probe's attenuator factor.
FULL — The DA1855A amplifier's full bandwidth, over 100MHz,
is passed to the oscilloscope, spectrum analyzer or digitizer.
Frequency response and transient response are essentially
independent of the oscilloscope's input impedance.
20 MHz — A 20MHz three pole (18dB/octave) filter allows the
DA1855A to reduce extraneous noise. This filter is a passive LC
ISSUED: July 2002
mode provides up to
DIFF
function is the same
DIFF
, i.e., any input attenuation multiplies
COMP
DA1855A-OM-E Rev A