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Tektronix FG 5010 User Manual

Tektronix FG 5010
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Input
Differential
Amplifier
.
This
circuit
consists
of
am
plifier
U1041B
,
transistors
Q1131
,
Q1132
,
Q1121A
and
Q1121B
plus
related
components
.
The
combination
of
VR1041
and
R1046
set
the
operating
point
for
this
circuit
.
The
approximately
7
V
at
the
non
-
inverting
input
of
U1041B
sets
the
current
through
both
Q1131
and
Q1132
.
The
first
transistor
furnishes
the
standing
current
for
the
amplifier
,
and
the
second
,
Q1132
,
provides
the
current
for
the
Multipli
er
stage
.
Current
through
Q1131
is
split
at
R1121
,
which
sets
the
amount
of
offset
to
compensate
for
any
input
offset
.
The
incoming
signal
is
applied
at
the
base
of
Q1121A
,
and
is
taken
off
the
collector
of
each
transistor
for
application
to
the
input
of
the
Multiplier
,
pins
11
and
12
.
Multiplier
.
This
circuit
is
a
monolithic
device
,
U1111
,
that
controls
the
Output
Drivers
,
Q1107
and
Q1106
.
Current
for
the
Multiplier
is
furnished
by
the
Multiplier
Current
Source
,
at
pins
2
and
3.
Incremental
control
and
amplitude
modula
tion
of
the
multiplier
output
is
furnished
by
amplifier
U1141B
,
which
also
causes
the
output
to
be
complemented
upon
CPU
command
.
The
output
of
U1252
is
fed
through
R1341
and
R1147
to
the
inverting
input
of
U1141B
.
The
output
of
U1252
also
passes
through
R1340
to
the
Comple
menting
Relay
.
The
signal
either
passes
through
the
relay
contacts
,
R1245
,
and
R1146
to
the
non
-
inverting
input
of
U1141B
,
or
that
signal
path
is
disconnected
and
R1245
is
connected
through
R1135
to
ground
.
The
net
effect
is
to
reverse
the
polarity
of
the
signal
out
of
the
Multiplier
.
The
output
of
the
Multiplier
is
taken
off
pins
5
and
6
and
applied
to
the
emitter
of
Q1107
,
the
Output
Driver
.
Potentiometer
R1122
sets
the
Multiplier
gain
.
DAC
.
This
circuit
consists
of
Digital
-
to
-
Analog
Converter
U1351
and
amplifier
U1252
.
The
AM
signal
and
reference
voltage
are
applied
to
the
input
pin
of
U1351
.
Data
from
latches
U1341
and
U1451
control
the
gain
of
the
stage
by
selecting
the
appropriate
internal
resistance
.
If
AM
is
select
ed
,
the
gain
is
halved
by
the
CPU
to
accommodate
the
addi
tional
current
.
When
the
AM
is
shut
off
,
the
output
of
U1252
sets
the
gain
of
the
Multiplier
.
Multiplier
Current
Sources
.
Amplifier
U1141A
and
tran
sistor
Q1134
form
a
current
source
that
supplies
current
to
the
Multiplier
stage
.
The
reference
for
the
stage
comes
from
the
divider
string
,
R1148
,
R1143
,
R1045
,
R1142
,
in
con
junction
with
VR1141
.
This
string
sets
the
output
of
U1141A
,
and
thus
the
conduction
of
Q1134
.
Output
Driver
.
This
circuit
consists
of
amplifier
U1041A
;
transistors
Q1133
,
Q1107
,
and
Q1106
;
plus
related
compo
nents
.
Current
for
the
output
is
provided
by
U1041A
and
Q1133
.
@
)
Theory
of
Operation
-
FG
5010
As
mentioned
earlier
,
R1148
,
R1143
,
R1045
,
R1142
,
and
VR1141
form
a
divider
string
that
sets
the
noninverting
in
put
of
U1041A
at
approximately
-9
V.
This
sets
the
con
duction
of
Q1133
.
Potentiometer
R1145
sets
the
gain
of
the
stage
to
allow
for
any
offset
difference
between
the
output
drivers
and
the
next
stage
.
The
Output
Driver
transistors
,
Q1107
and
Q1106
,
form
a
single
-
ended
common
-
base
current
-
drive
stage
.
The
Multi
plier
drives
the
emitter
of
each
transistor
,
and
the
output
is
taken
off
the
collector
of
Q1107
.
AM
Circuits
The
AM
Circuits
consist
of
Buffer
U1441
,
transistor
Q1042
,
field
-
effect
transistors
Q1041
and
Q1151
,
amplifiers
U1251A
and
U1251B
,
plus
related
components
.
The
AM
signal
from
the
front
-
panel
connector
comes
through
R1051
to
the
source
of
Q1151
.
Zener
diodes
VR1042
and
VR1052
limit
the
input
signal
excursion
to
8
V
peak
to
peak
to
protect
Q1151
.
A
switch
is
formed
by
Q1151
and
Q1041
to
enable
or
disable
the
AM
signal
.
The
Q8
bit
from
U1551
(
Diagram
25
)
is
applied
to
Buffer
U1441
,
which
in
turn
controls
Q1042
.
Zener
diode
VR1051
shifts
the
signal
level
to
fit
Q1042
.
Depending
on
the
conduction
state
of
Q1042
,
Q1151
conducts
,
passing
the
AM
signal
,
or
is
shut
off
and
Q1041
conducts
the
input
of
U1251A
to
ground
.
The
AM
signal
that
passes
through
Q1151
is
applied
to
amplifier
U1251A
,
which
amplifies
the
signal
by
about
2
.
From
the
output
of
U1251A
,
the
signal
is
summed
with
the
reference
voltage
set
by
R1251
,
VR1341
,
R1156
,
and
R1155
.
The
combined
signal
is
fed
from
the
output
of
U1251B
to
the
input
of
the
DAC
.
OUTPUT
AMPLIFIER
AND
ATTENUATION
Introduction
The
major
circuits
depicted
on
Diagram
25
are
the
Out
put
Amplifier
,
Step
Attenuator
,
and
Latches
.
The
latches
are
discussed
at
the
first
of
the
Output
Section
discussion
.
The
signal
from
the
Multiplier
stages
is
applied
to
the
Output
Amplifier
.
Following
amplification
,
the
signal
passes
through
the
Step
Attenuator
to
the
output
connector
.
Output
Amplifier
This
circuit
is
a
current
-
driven
operational
amplifier
that
has
a
gain
of
approximately
3.3
V
per
milliampere
.
The
am
4-33

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Tektronix FG 5010 Specifications

General IconGeneral
BrandTektronix
ModelFG 5010
CategoryPortable Generator
LanguageEnglish

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