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W
i
d
t
h
Ge
n
erator
T
his section is on schematic 6E.
Variab le Amplitude and Slope Gen erator
This section is on schematic 6F .
HP 8110 Α Service Gui de
T
aking the delayed pulse as the starting
p
oint, the output pulse is
now generated at α specified width . Operation
o
f
t
his section is
functionally s imilar to that of
t
he
D
elay Generator, with DAC
U
152
p
roviding α reference v oltage for the operation
o
f Q150, Q151 and
Q153 .
U
155
p
erforms the current range switching .
I
t uses α
S
LAVE (SLope Amplifier VErnier)
I
C to generate the
l
eading and trailing edge ramps of
t
he output w aveform .
The SLAVE IC generates highly stable, accurately controlled ramps
u sing α s ingle integrated capacitor, plus external
capacitors and
external
c
urrent sources .
The
E
CL differential signal from the Width Generator i s
buffered
and input to the slope generator . Capacitors C212
to C217 are
switched by Q200 - Q201 and Q202A, Β
a
nd C .
E
ach capacitor
represents α slowing of
t
he ramp by α
f
actor of 10 . The final (slowest)
stage i s
p
rovided by
t
he capacitance
m
ultiplier
f
ormed by U220 and
associated components, giving α gain
o
f 100 .
T
his avoids the use of α
relatively large electrolytic capacitor .
R
eed relay Κ 220 s witches this
stage .
Slope Curre n ts
This section is on schematic 6G .
There are 2 separate slope currents applied :
f
ast and slow . The f ast
slope current
m
akes use of an integrated capacitor in t he SLAVE
IC, and enables f ast slope times in t he range of <2
to 20ns .
F
ast
and slow slope currents are sourced to and sunk from t he SLA
V E
IC, u sing similar circuitry. Only
t
he current sourcing circuitry is
described here :
DAC
U
250, buffered by U252
p
rovides α reference voltage at the
emitter of Q250 . The current flow is mirrored by Q251 and Q252, the
f
ast and slow slope current generators .
Vernie r currents
This section is on schematic 6Η .
I
t
p
rovides
p
recise control
o
f waveform
a
mplitude .
Multiplexer
U
304 selects 1, 2 or 3 current sources, depending
on the
range required :
F
unctional Descri ption 7-3 1
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