5 - 4
5-3 FREQUENCY SYNTHSIZER CIRCUITS
VCOs (MAIN-A/-B UNIT)
The TX VCO which generates the TX signal is composed
by Q13, D16, D18, L27, L38, etc., and the frequency
modulation is carried out by applying modulation signals to
D18.
The RX VCO which generates the 1st LO signals is
composed by Q14, D33, L39, etc.
These two VCOs are switched by the VCO SW (Q15, 16)
using “RXC” signal.
The output signal from each VCO is amplifi ed by the buffer
AMP (Q11) and LO AMP (Q10), and then applied to the TX
or RX circuits.
A portion of generated signals is applied to the PLL IC (IC4)
via buffer AMP (Q12).
PLL (MAIN-A/-B UNIT)
The applied VCO output is divided according to the serial
data including divide ratio from the CPU, at the prescaler
and programmable divider. In the same way, the reference
frequency signal from the reference frequency signal
oscillator is applied to the PLL IC and divide so that these
are the same frequency.
The frequency-matched signal is applied to the phase
comparator and phase-compared. The resulted phase
difference is detected as a phase-type signal, and level-
adjusted at the charge pump then output. The output pulse
type signal is passed through the loop filter to be converted
into the DC voltage (=Lock Voltage).
Applying the lock voltage to the variable capacitors
(VD) which composes a part of the resonator of VCO,
the capacitance of VDs changes corresponding to the
applied lock voltage. This causes the change of resonation
frequency that determines the VCO oscillating frequency to
keep the VCO frequency constant.
When the oscillation frequency drifts, its phase changes
from that of the reference frequency, causing a lock voltage
change to compensate for the drift in the VCO oscillating
frequency.
• FREQUENCY SYNTHESIZER CIRCUITS
5-4 VOLTAGE DIAGRAM
Voltage from the power supply is routed to the whole of the transceiver via regulators and switches.
LPF
REF
X2
LO
SW
D14,D15
Q14,D33
Q13,D16
FIL
RIPPLE
Q17
VCO
SW
Q15,16
FIL
LOOP
PLL
IC
IC4
X3
Q34
FM
MOD
D18
BPF
BUFF
Q10
BUFF
Q11
LPF
IC19
AMP
X2
Q12
BPF
TLV
ADJ
D53
RLV
ADJ
D52
IF IC
8V
RXC
RX VCO
TX VCO
IC1
REF
15.3MHz
Clock,Data,Strobe
45.9MHz
182.35 MHz-220.35 MHz
136/146 MHz-1740 MHz
TXC
T8V
RLVA
TLVA
LV
LV
SW
POWER
Q23,Q24
+5
5V
REG
Q27, Q28
+8
REG
IC9
T8
REG
Q25,Q29,D23
W2
Power supply cable
REG
CPU5
IC10
Q26,Q30
R8
REG
Drive AMP(
Q9
), APC AMP(IC2), etc.
IF IC (IC1), PLL IC(IC4), etc.
RF AMP(Q2), 1st IF AMP(Q4), 1st mixer(Q3), etc.
External output(from J6)
VCOs, FRONT UNIT
T8V
R8V
8V
VCC
TMUT
RXC
PWON
HV
CPU5
CPU5
VCC
8V
8V
8V
HPA module(IC3)
HV
