HP 8112A, Operating, Programming And Servicing Manual

Page: 207 / 406

Slope Generation
FRCl1 WIDTH
I
TRIG IN
RAt'P
'
a=FACITOR :
.
;
GENERATOR
-s.2v
CCNTRCL SIGR.... FIXED
13
_J
SLCF'E
21
EECL
JUL.r
EXT
SQ-IMtTT TRIGCER
ADJUST
14 La.I LEVEL
+6.2V
OUT BIAS
R:3 1 a .
.
l2.srnA
Figure 1 0.3-3. Slope IC block diagram
Refer to Figure 1 0.3-5 and Figure 1 0.3-3. When triggered by the
output of the width generator, the Slope IC U301 operates in one of
two transition modes.
Fixed Transition
In fixed mode
(
fixed 4.5 ns transitions
)
, an ECL trigger output is
used by the Shaper IC
(
See Chapter 10.4) to produce fixed transition
time output pulses.
With fixed mode selected, the input trigger signal on pin 1 is
passed via ECL circuitry to the EECL output, pin 2 1 . See Figure
Figure 1 0.3-3. An error output is available at pin 23, this goes active
if a trigger input is detected whilst the IC output is still active.
Linear and Gaussian Transitions
In linear and gauss slope modes, a differential output
(
OUT, OUT
)
is used to drive the Shaper IC
(
See Chapter 10.4) to produce output
pulses with variable transition times.
When linear or gaussian mode is selected, the slope generator relies
on four current sources and a switched range capacitor network
to produce variable transition time leading and trailing edges,
depending on the LEE and TRE DACs in the control section
(
See
Chapter 10.5). The slope ramp value is controlled internally, or
externally, according to the condition of pin 1 0
(
EXT
)
.
Servicing the Timing and 1 0.3-7
Slope Generators