HP 8340b User Manual

Reference
Loop
Theory
of
Operation
The
reference
loop
produces
all
of
the
reference
signals
that
are
used
in
instrument phase-locked
loops.
Each
of
these signals
are
referenced
to either
the
internal
A5110
MHz standard
or
an external
5
or
10
MHz
source
connected
to
the
EXT
REF
BNC
connector
on
the
rear
panel.
The
frequency
stability
of
the
instrument
is
directly
related
to
the
stability
of the
reference.
The
reference
loop consists
of
four
assemblies,
shown
in
functional
order:
•
A30100
MHz
VCXO
assembly
•
A29
reference phase
detector
assembly
•
A34
reference
loop
—
M/N
loop
motherboard
•
A5110
MHz
standard
A30
100
MHz
VOLTAGE CONTROLLED CRYSTAL OSCILLATOR
ASSEMBLY
The
A30 VCXO
assembly
is
a
crystal-stabilized
voltage
controlled oscillator with
a
±1 kHz tuning
range.
It
provides
a 100
MHz
reference
signal
for four
instrument
circuits:
•
20-30
phase
lock
loops
(PLL3)
•
3.7
GHz oscillator
(in
the
RF
section)
•
M/N
phase
lock
loop
(after
being
multiplied
by
four)
•
A29
reference
phase
detector
for
phase-locking
to the
10
MHz
standard
The
A30
VCXO
is
phase-locked
to
the
A51
frequency
standard
by
the
A29
reference
phase
detector
assembly.
A29
REFERENCE
PHASE
DETECTOR ASSEMBLY
The
reference
phase detector phase-locks
the
A30
VCXO
to the
A5110
MHz
reference standard.
This
assembly
also
divides the
output
of the
A30 VCXO
and
distributes
it
to
the following circuits:
•
M/N
phase
lock
loop
•
20-30
phase
lock
loops
(PLL1,
PLL2)
•
10
MHz
OUT
on
the
rear
panel
The
100
MHz
VCXO
output
is
divided
by
ten,
providing
a
10
MHz input to
the
reference
phase
detector.
The
10
MHz
(internal
or
external)
frequency
standard
is
the
second
input
to
the
reference
phase
detector.
The
VCXO
tuning
voltage
output
is
proportional
to
the
error
in
the
100
MHz
VCXO.
This
assembly
also
divides
the
100
MHz
VCXO
output
frequency
by five
and
ten,
providing 20
MHz
and
10
MHz
respectively.
The
20
MHz
signal
is
output to
the
M/N
phase
lock
loops.
10
MHz
is
output
to
the
20-30
phase
lock
loops
and
to the
rear
panel
10
MHz
REFERENCE
OUTPUT
connector.
B-2
Reference
Loop
Theory
of
Operation
HP
8340B/41B

HP 8340b Specifications

General

Brand	HP
Model	8340b
Category	Inverter
Language	English