Operation Model
8904A
THE SIGNAL FOR THE FIRST ADDRESS
Polarity
Outputs
These TTL signals identify the polarity of the associated channel's waveform. The output
is
high for
phases of
0"
to
180",
and low for
180"
to
360".
These outputs are available with all instrument configurations; regardless
of
what options are present
in your instrument.
NOTE
Changing the Phase setting
of
the signal to be output alters
the
phase
relationship between the signal and its corresponding polarity signal.
Polarity signal transitions are only exactly aligned with the signal being
output when the Phase
is
set to
0".
These outputs are used in the Channel Configuration mode only.
Circuit Gnd
This
is
the same as chassis ground.
Hop
Register Address
These four connections are used
to
specify Hop
Ram
address
for
fast
hopping channel
A's
frequency,
phase, and amplitude (Option
003
only).
Once you have accessed the Hop Menu and set the desired Hop
Ram
parameters
for
each address, you
can output the signal
for
each address by turning the Digital Port
ON,
and then setting the appropriate
address on these connections.
As
each Hop
Ram
address
is
set on these pins, the corresponding
channel
A
configuration
is
output.
There is a delay between the time the address
is
set on the Digital
Port
and the time the signal appears
at the instrument's output. This delay
is
typically
<8
ps.
The maximum rate that new addresses can
be changed is about
400
kHz (every
2.5
,us).
A
schematic showing an example
of
a circuit used
to
fast
hop
is
provided in the
Option
009
section
of
the HP
8904A
Multifunction Synthesizer
Operation and Application
guide.
The timing diagram below illustrates
fast
hopping the signal at the maximum rate of
400
kHz (changing
the address on the Hop Register Address
pins
every
2.5
ps).
Figure
3-7.
Fast
Hop
Timing Diagram
THE HOP
RAM
ADDRESSES ARE
CHANGED
ON
THE HOP REGISTER
ADDRESS PINS, THEN..
.
3-16
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