Motorola GP340 ATEX, Информация о сервисе, Страница: 13 / 43

Frequency Generation Circuitry 2-7
In achieving fast locking for the Synthesizer, an internal adapt charge pump provides higher current
at pin 45 of U201 to put synthesizer within the lock range. The required frequency is then locked by
normal mode charge pump at pin 43 .
Both the normal and adapt charge pumps get their supply from the capacitive voltage multiplier
which is made up of C258, C259, C228, triple diode
c
R201 and level shifters U210 and U211. Two
3.3V square waves (180 deg out of phase) are first shifted to 5V, then along with regulated 5V , put
through arrays of diodes and capacitors to build up 13.3V at pin 47 of U201.
D A T A (U 4 0 9 PIN 100) ■
C L O C K (U 4 0 9 PIN 1) ■
C S X (U 4 0 9 PIN 2)
M O D IN (U 4 0 4 PIN 40>
+ 5 V (U 2 4 7 PIN 4)
(U 2 4 8 PIN 5)
10
13, 30
36
23
24
25
32
47
V O L T A G E
M U L T IP L IE R
D A T A
L O C K
C L K
F R E F O U T
C E X
U251
G N D
M O D IN
L O W V O L T A G E
F R A C T IO N A L -N
IO U T
V CC, D C 5 V
S Y N T H E S IZ E R
IA D A P T
V DD, 3 3 V
M O D O U T
XTA L1
A U X 4
X T A L 2
A U X 3
W A R P
S F O U T
P R E IN
V C P
BIAS1
V M U L T 2
V M U LT 1 A U X 1 B IA S 2
L O C K (U 4 0 9 PIN 56 )
F R E F (U 201 PIN 21 & U 404 PIN 34)
S T E E R IN G
LIN E
15
48
5 V
P R E S C A L E R IN
LO R F IN JE C T IO N
T X R F IN JE C T IO N
(1 S T S T A G E O F PA)
D U A L
T R A N S IS T O R S
7
8
9
Figure 2-4 Synthesizer Block Diagram