Figure 4-5 – Motorola CP150TM User Manual
Page 33
6880309N62-C
June, 2005
136-162 MHz VHF Theory Of Operation: VHF Frequency Generation Circuitry
4-7
C267, and varactor D261. High-port audio modulation from the synthesizer IC is applied as
VCO_MOD to varactor D262 which modulates the transmit VCO.
Figure 4-5. VHF VCO Block Diagram
Presc
RX
TX
Matching
Network
Pin 8
Pin 14
Pin 10
3V (U330 Pin 5)
VCC Buffers
U201 Pin 32
AUX3 (U201 Pin 2)
Prescaler Out
Pin 12
Pin 19
Pin 20
TX/RX/BS
Switching Network
U251
VCOBIC
Rx Active
Bias
Tx Active
Bias
Pin 2
Rx-I adjust
Pin 1
Tx-I adjust
Pins 9,11,17
Pin 18
Vsens
Circuit
Pin 15
Pin 16
TX VCO
Circuit
TX
Tank
RX VCO
Circuit
RX
Tank
Pin 7
Vcc-Superfilter
Collector/RF in
Pin 4
Pin 5
Pin 6
RX
TX
V_SF (U201 Pin 28)
NC
NC
Vcc-Logic
3V
(U330 Pin 5)
Steer Line
Voltage
(V_STEER)
Pin 13
Pin 3
TRB_IN
Buffer
Q280
RX INJ
V_SF
(U201 Pin 28)
TX INJ