Motorola GP344 Detailed Service Manual page 160

1-10
Both the normal and adapt charge pumps get their supply from the capacitive voltage multiplier
which is made up of C3701 to C3704 and triple diodes D3701, D3702. Two 3.3V square waves (
180 deg out of phase) are first multiplied by four and then shifted, along with regulated 5V, to build
up 13.5V at pin 47 of U3701.
DATA (U409 PIN 100)
CLOCK (U409 PIN 1)
CSX (U409 PIN 2)
MOD IN (U404 PIN 40)
+5V (U3711 PIN 4)
5, 20, 34, 36
(U3201 PIN 5)
REFERENCE
OSCILLATOR
VOLTAGE
MULTIPLIER
7
DATA
8
CLK
9
CEX
U3701
LOW VOLTAGE
10
MODIN
FRACTIONAL-N
13, 30
SYNTHESIZER
VCC, DC5V
VDD, 3.3V
23
XTAL1
24
XTAL2
25
WARP
32
PREIN
47
VCP
VMULT2 VMULT1
14
15
PRESCALER IN
Figure 5-2 Synthesizer Block Diagram
4
LOCK
19
FREFOUT
6, 22, 23, 24
GND
43
IOUT
45
IADAPT
41
MODOUT
3
AUX4
2
AUX3
FILTERED 5V
28
SFOUT
BIAS1
40
BIAS2
AUX1
39
48
R5
DUAL
5V
TSTRS
THEORY OF OPERATION
LOCK (U409 PIN 56)
FREF (U3220 PIN 21 & U404 PIN 34)
STEERING
LINE
2-POLE
LOOP
FILTER
LO RF INJECTION
VOLTAGE
CONTROLLED
OSCILLATOR
TX RF INJECTION
(1ST STAGE OF PA)