Hytera PT580, Service Manual, Page: 11 / 104

Service Manual
This interface is used to transfer the charging voltage signal from the PLL to the RX IF VCO.
(5) FLout IF
This interface is used to transfer the charging voltage lock signal from the PLL to the RX IF VCO.
(6) FLout RF
This interface is used to transfer the charging voltage lock signal from the PLL to the TX/RX VCO.
(7) SYNTH_LOCK
This interface is used to transfer the PLL lock indication signal to the baseband. When this pin outputs
high level signal, it indicates the PLL is locked.
(8) SYN_ON
This interface is used to transfer the PLL enable signal from the baseband. It outputs 3.3V voltage, and
is open in normal status.
(9) 12MHz_REF
This interface is used to transfer the reference frequency for the PLL.
1.4 VCO
VCO VCO
BP filter
BUFFER BUFFER
TRIPLE
5V SYN _ ON
TX LO
RX LO
RVO SWITCH
TVO SWITCH
RX LO OUTPUT
TX LO OUTPUT
Figure 5 Diagram of VCO
The working principle of the VCO is described below:
The PLL outputs the control voltage CV. When the RX VCO is locked, it will be output to the receiver via
the BUFFER. When the TX VCO is locked, it will be output to the receiver via the BUFFER, TRIPLE and
filter. The VCO that is powered up will be locked.
The interfaces between the VCO and the baseband or other circuits are described below.
(1) CV: This interface is used by the PLL to output control voltage.
(2) RVO SWITCH: This interface is used to supply power to the RX VCO.
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