Rf Module; General; Functional Description; Control- And Output-Signals - Benefon DELTA TDP-40-TN2 Service Manual

6.3 RF MODULE

RX Synthesizer
OS0320 Synthesizer

6.3.1 General

The RX synthesizer generates an upper side injection frequency for the receiver.
The injection frequency is fed to the receiver's first mixer.
Operating voltage
Current consumption
Output level to the receiver
Frequency range

6.3.2 Functional Description

The RX injection frequency is generated with a phase locked loop. The VCO pro-
duces the injection frequency determined by the control voltage. After the VCO
stage comes the amplifier stage Q350. After the amplifier stage, part of the signal is
fed to the synthesizer circuits I302 divider. The synthesizer circuit contains a pre-
divider, programmable divider, reference frequency divider, and a phase comparator.
The synthesizer circuit produces pulses at two outputs as a result of the phase-shift
comparison, which are converted to current pulses by the charge pumps Q301 and
Q302. The current pulses either charge or discharge the loop filter. The VCO control
voltage is derived from the loop filter output.
The synthesizer 25 kHz reference frequency is made by dividing the 12.8 MHz sig-
nal from the temperature compensated oscillator (TCXO). The series-form signal
which controls the channel frequency comes from the audio/processor-modules via
the X-RF connector. SDATA and SCLK signals are common to both TX- and RX-
synthesizers. A positive pulse in the SRE line loads the division ratio (corresponding
to the channel frequency of the channel) fed to the SDATA line, to the synthesizer
circuit I302.

6.3.3 Control- and Output-Signals

VRX
SCLK
SDATA
SRE
RX-INJ
XS030ZE4_fm5.fm
RX synthesizer operating voltage
Clock signal for the synthesizer control data
Synthesizer control data
ENABLE pulse to the synthesizer
RX synthesizer output to the receiver
Product: TDP-40-TN2 (Delta) /
28.1.1999
4.75VDC
15 mA
+1 dBm
540,25...544,725 MHz
OS0320 Synthesizer
4.75V
+1 dBm
37