HP 83480A User Manual

How the Instrument Works
Standard and Enhanced Trigger Modes
12 GHz/Gate mode (Option 100 only)
The 2-12 GHz Gate mode will trigger selectively on distinct groups of high
speed signals. It is the most complex trigger mode of the analyzer and is
primarily intended for experienced users.
As in the 2-12 GHz mode, a high-speed IC is used to divide the incoming
signal frequency by a factor of 16. This divided signal is applied to the
existing trigger circuitry. The trigger input is AC-coupled to the divider IC.
A low speed ( < 1 MHz maximum frequency) TTL level gating signal is applied
to a
BNC connector
on the
rear
panel
of
the
analyzer
.
Only
when
that
signal is
at a
logical high
will
the
trigger
divider
recognize
input
transitions
.
Because the
speed of
the
gating
function
is
much
less
than
that
of
the
trigger
input,
there
must
be
some
signicant
separation
of
the desired
and excluded
trigger
signals
.
This
mode
,
if
used
to separate
out individual
segments
of
a
continous
trigger
,
will
result
in
trigger
artifacts
.
Refer
to the
Trigger
Artifacts
section
later
in
this
chapter
for
additional
information.
The
gate
mode allows
measurements
of
signals
that
previously
were
dicult,
or
even
impossible
,
to
view
.
However
,
there
are
signicant
tradeos
.
The
rest
of
this
section
discusses
the
tradeos
and
oers
suggestions
on
how
to
minimize
their
impact,
T
rigger
sensitivity
In
the
gate
mode
,
the analyzer
should only
trigger
when
both
the
gate
enable
signal
is
present
and
a
trigger
transition
occurs
.
Therefore
,
the
free
running
eect
of
the
divided
trigger
is
suppressed
by
biasing
the
divider
IC
to
prevent
self-oscillation. This reduces the sensitivity of the trigger. In the standard
divided mode, the jitter is specied as 2 ps rms from 2 GHz to 12 GHz with a
200 mV p-p sine wave input. See Figure 13-13.
13-25

HP 83480A Specifications

General

Brand	HP
Model	83480A
Category	Measuring Instruments
Language	English