Frequency Generation - LG U400 Service Manual

3. Technical Brief

3.8.3 Frequency Generation

The Wopy (W-CDMA Receive ASIC) contains the active elements for a 13MHz VCXO, which is
designed to be the reference frequency of the UE.
There are two synthesizers in the W-CDMA part of the radio, an intermediate frequency (IF)
synthesizer and a radio frequency (RF) synthesizer. They generate the Intermediate Frequency Local
Oscillator (IFLO) and Radio Frequency Local Oscillator (RFLO) signals. Both synthesizers are used in
both the transmitter and the receiver, which gives the radio a fixed duplex distance of 190MHz.
The RF synthesizer is in the Wopy (W-CDMA Receive ASIC), except for the loop filter, which is
external. The 13MHz clock is used as the reference, and the phase detector frequency is 200kHz. The
programmable divider makes the RF synthesizer cover the 2300~2360MHz band.
The IF synthesizer is in the Wivi (W-CDMA Transmitter ASIC), except for the loop filter.
The 13MHz is used as the reference, and the phase detector frequency is 1MHz. The IF VCO runs at
1520MHz given that the (programmable) reference divider is set to 13.
The synthesizers are controlled by Wanda (W-CDMA digital base-band coprocessor ASIC) via the
serial bus to Wivi (W-CDMA Transmitter ASIC) and Wopy (W-CDMA Receive ASIC).
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