NSW-6
System Module SE2
PAMS Technical Documentation
Page 44
Issue 1 12/99
Nokia Mobile Phones Ltd.
VCTCXO. Frequency of the oscillator is 19.44 MHz. It is controlled by an
AFC voltage, which is generated in the base band circuits. In digital mode
operation, the receiver is locked to base station frequency by AFC. Next
to detector diode, there is a sensor for temperature measurement. Volt-
age RFTEMP from this sensor is fed to baseband for A/D conversion.
This information of the RF PA–block temperature is used as input for
compensation algorithms.
The ON/OFF switching of the VCTCXO is controlled by the sleep clock in
the baseband via RFCEN. Other parts of the synthesizer section are 1
GHz VCO, 2 GHz VCO, VHF VCO, PLL for 2 GHz VCO and PLL sections
of the EROTUS IC.
DAMPS 800 operation
1GHz UHF synthesizer generates the down conversion injection for the
receiver and the up conversion injection for the transmitter. UHF fre-
quency is 985.20 ... 1010.16 MHz, depending on the channel which is
used. 1GHz UHF VCO is a module. The PLL circuit is dual PLL, common
for both UHF and VHF synthesizers. These PLLs are included in the
EROTUS IC.
LO signal for the 2nd RX mixer is multiplied from the VCTCXO frequency
as described above.
VHF synthesizer is running only on digital or analog traffic channel.
322.38 MHz signal (divided by 2 in EROTUS) is used as a LO signal in
the I/Q modulator of the transmitter chain.
TDMA 1900 operation
2 GHz VCO with external PLL circuit generates 2046.24 ... 2106.18 MHz
injection signals for 1st RX mixer and TX upconverter.
VHF synthesizer is running only on digital traffic channel. Operating fre-
quency 392.46 MHz is fed to EROTUS modulator, where it is divided by 2
and used as modulator LO signal.
Transmitter
DAMPS800 TX
The TX intermediate frequency is modulated by an I/Q modulator con-
tained in the transmitter section of EROTUS IC. The TX I and TXQ sig-
nals are generated in the COBBA_D interface circuit and they are fed dif-
ferentially to the modulator.
Intermediate frequency level at the modulator output is controlled by
power control.
The output signal from EROTUS modulator is filtered to reduce har-
monics and RX–band noise. The final TX signal is achieved by mixing the
