Fluke 93 - Generator

3-30
CIRCUIT DESCRIPTIONS
3.4.7
GENERATOR circuit
•
Introduction
See figure 3.14.
The
ScopeMeter has a bullt-ln signal
generator, which can produce
the following signals, used to
adjust the probes:
•
square wave voltage.
amplitude:
frequency:
•
DC voltage: 3V
ScopeMeter model 97
can also produce:
‘
sine wave voltages,
ampi Itu
de
:
frequency:
-
square wave voltages,
amplitude:
frequencies:
-
slow ramp voltage,
-2V...+2V
-
slow ramp current.
-3
mA,..43mA
5V peak-to-peak
976 Hz
5V peak-to-peak
976 Hz
5V peak-to-peak
488 Hz
1-95
kHz
The signal generator
uses a square wave voltage,
coming from the D-ASIC to generate
the various
signals. The circuit
consists of an operational amplifier,
a fourth order filter,
and a current source. The
configuration can
be changed by means
of
programmable
switches to produce
different output
signals.
-
Detailed circuit
description
See figure 3.16 and circuit
diagram A2b (figure
10,6).
Figure 3.16 shows the basic
generator circuitry:
••5V
Figure 3.
16 Basic generator circuitry
This circuft uses a square
wave voltage, STIMUL, coming
from the D-ASIC. This signal has
an
amplitude between OV and
+5V. The duty cycle of
the square wave signal Is varied
depending on the
signal to be generated.
The reference voltage +Vref
is used to generate the DC voltage.