Synthesizer; Transmitter (Tx) - Nokia 300 Service Manual

RM-781
System Module

Synthesizer

The synthesizer has separate highly integrated 4GHz VCOs for RX and TX. The integrator capacitors of the loop
filter are outside of the IC. The PLLs are fractional type of dividers.
The reference oscillator is an on-chip 38.4 MHz digitally controlled oscillator. The 38.4 MHz crystal is outside
of Älli. DCXO delivers the internal clock to Älli, differential clock signal to BB, and two single mode clock signals
to NCW modules. Älli delivers a clk signal to diversity RX. The oscillator is controlled via RFBus with AFC signal.
Temperature compensation of the oscillator is running by the SW in Älli. The temperature sensor itself is
outside of Älli.

Transmitter (TX)

The main features of Linko1 transmitter are:
• Common PA for GSM and WCDMA
• High and low band signal paths
• Low band: 824 - 915 MHz
• High band: 1710 - 1980 MHz
• Two operation modes in PA
• Saturation mode in GMSK usage
• Linear mode in Edge and WCDMA usage
• No TX filter between PA and Älli
• Common regulators for GSM and WCDMA
• Boost and SMPS regulators in Aura
• Feeding the supply voltage to PA
• Operation frequency varies depending on the used system
Frequency
WCDMA
GSM
• Digital interface to baseband
• WCDMA mode
• Digital IQ interface
• 3 data and 1 clk signals
• GSM mode
• GSM TX data bits are sourced from baseband via RFBus to Älli
In GMSK mode, the output level of Älli is kept high with all power levels, and the output power is adjusted
by altering the collector voltage of PA. In practice, the output level of Älli is also slightly changed (optimized)
in the highest power level to keep the PA compression level more constant, which results in better overall
efficiency and performance.
In WCDMA and EDGE mode, the output power is tuned by output level of Älli. The supply voltage in WCDMA
mode is adjusted in power levels to optimize the current consumption.
Issue 1
SMPS
3.0 MHz (typ)
9.5 MHz
COMPANY CONFIDENTIAL
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Boost
4.5 MHz (typ)
7.5 MHz
DCDC
1.3 MHz (typ)
2.7 MHz
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