Tektronix FG 5010 User Manual

Theory of
Operation -
FG 5010
V
UP
VON
4-14
2R
20R
200R
1R
1ØR
1BØR
RNG1
RNC2
RNG3
RNG1
RNG2
RNG3
UP DN
DN
V.
and V
voltages from the Symmetry circuits are ap
plied to the input of the upper section of the amplifier , and
the
V
voltage is applied to the input of the lower section of
the
amplifier .
Depending on the loop
frequency range , one of
the three ranges of resistance is selected to provide the
proper input resistance to the amplifiers . Out of the two
amplifiers ( upper and lower ) comes a voltage that is propor
tional to the applied voltage and the selected resistance .
The voltage from the two amplifiers is applied to the two
Shrink Current Sources , which furnish the shrink current to
the Level Detector .
At
lower
frequencies
,
component
propagation delay
is
minimal
and
has little
or no effect
on loop
performance
.
At
higher frequencies , however , performance can be degraded
significantly if no measures are taken to compensate for the
delay . Figure
4-7
illustrates
a
stylized
pair of
triangle
waveforms
that
are different in
ramp rate . The
reader should
note
that these two
figures
are
exaggerated for
purposes of
explanation . In the figure , T is the constant delay that oc
curs for an event to transit the loop , or otherwise stated , the
time that elapses from the moment that the Level Detector
perceives the
triangle
to
be at the
upper
switching
potential
to the time that
the triangle
actually
reverses
direction
. Note
that the
switching
potential KV
is
slightly
lower
than
the
triangle peak in both cases to compensate for the delay at
UP
KH
U1641A
마
Fig
. 4-6 .
Simplified
diagram of
Shrink
Circuits .
U1641C
U1641B
Q1241
+ V
+ 10.ØV
UP SHRINK
CURRENT
LVL
.
DET .
+
10.0V
DN SHRINK
CURRENT
U16410
Q1242
Q1531
3467-13
faster ramp rates . As the ramp changes , the delay remains
unchanged , so the faster - rising signal ( dashed line ) will sig
nificantly overshoot the planned triangle peak . To overcome
this , the Shrink Control Current Sources produce the cur
rent necessary to shift the switching point to compensate
for a change in slope . At lower ramp rates , the correction is
not
required
.
UP DN
1
Refer to Fig . 4-8 , which is a simplified diagram of the
Level Detector and Shrink Control Current Sources . For the
moment , assume that V
and V
are equal and opposite .
These two voltages are proportioned to the symmetry , and
are discussed later . Assume that the left half of U1351A is
cut off , which means that the triangle is on the down slope .
This also means that all of I , is steered through Q1342 .
Thus , the current through R1343 - R1344 is the 12
shrink
cur
rent only , so the switching potential of the circuit is con
trolled by , and is thus the lower of the two switching
potentials . When the triangle wave crosses the lower point ,
the left side of U1351A conducts , and Q1342 is cut off . The
I , current is steered through Q1341 to cancel some of the 12
current and raise the voltage at the collector of Q1341 . This
is the upper switching potential .
To avoid the
overshoot
problem
at
higher
frequencies ,
the shrink circuits remove current bias at the three highest
U
U
U
U
U
بال
U
U

Tektronix FG 5010 Specifications

General

Brand	Tektronix
Model	FG 5010
Category	Portable Generator
Language	English