Technics ST-9038 User Manual

t
PART
II
PLL SYNTHES]ZER
t
1.
PLL
Synthesizer
1-1
Synthesizer
Dividing
or multiplying
a certain
frequency
or combining
frequencies
to obtaín
the desired
frequency
is called
"frequency
synthesis" A frequency
synthesizer
is a
unit used to achieve
this
purpose.
1-2
Block
diagram of
synthesizer
section
98.3
(98.8)
-
118.6 MHz
1/A
1/983
(1/988)
-1/11a6
12.5
KHz
1
/ 1024
Xtal
12.8 MHz
ü
o
l
Ð
"
Frequency
range
87.6
(88.1)
-
107.g
MHz
.
Local
oscillator
frequency
gB.3
(gB.B)
-
118.6
MHz
.
1/8
prescaler
12.2815
(12.95)
-
14.B25MHz
"
Dividing
ratio of
programmable
frequency
divider
983
(988)
-
1 1Bo
.
Comparison
frequency
12.5
k1z
Note)
Values
in
parentheses
are
specif ied
for the
U.S.A.
When
a broadcast
signal
of
87.6
(88.1)
to 1Oj.g
MHz
enters
the
receiver,
the
local
oscillator
frequency
(Vco)
becomes
98.3
(98.8)
to 118.6
MHz.
The frequency
is
divided
ar rhe
ratio of
1/g
by
the
prescaler
through
the
interface,
and further
divided
ar rhe rario
of 1/gB3
(1i98g)
-
1/11g6
by
the
programmable
frequency
divider
according
to the
input frequency
thus
obtaining
12.5
KHz.
On the
other
hand,
a12.8MHz
frequency
from
a high
precision
crystal
oscillator
is
divided
at the
ratio
of
1/1024
to
obtain
12.5
KHz,
the
standard
comparison
frequency.
When
these two
frequencies
are added
to
the
phase
comparaTor,
itsoutput
is the
phase
difference.
By
passing
the
output
through
the low-pass
filter,
a
positive
or
negative
voltage
can be obtained
in
proportion
to
the
phase
difference
between
the
two
frequencies.
Vco
is
controlled
by this voltage.
As is evídent
in
the
above description,
the
composition
of
this
circuit
is
that
of a
pLL
synthesizer.
The
description
of
each
section
ís
given
in
the following.
1-3
lnterface
circuit
This
circuit
connects
Vco and
prescaler,
and serves
as an
amplifier and a buffer.
TR901
is a buffer
for
Vco
and
ECL
(Emitter
Coupled
Logic
lC), and
TRg02 is
a
buffer/amplif
ier for ECL
and TTL.
Vco
I nterface
Prescaler
Programmable frequäncy
d ¡vider
Low-pass
f ilter
Phase
comparatof
F
req
uency
d ¡vid er

Technics ST-9038 Specifications

General

Brand	Technics
Model	ST-9038
Category	Tuner
Language	English