M
ODEL
SL599 V
ERSION
V_1.0
P
REPARED BY
H/W
D
ATE
2007.04.11
S
UBJECT
T
ECHNICAL
M
ANUAL
P
AGE
48/52
SL599
T
ECHNICAL
M
ANUAL
3.
TX VCO
Two power VCOs are integrated with OPLL to form a complete transmitter circuit. The TX VCO
output power is typically 9dBm with +/-2.5dB variation in GSM850 bands and +8dBm output power
with +/-2dB variation in PCSL599900 bands over extreme Temperature conditions.
The PAM(RF3146) Input range is Typically 3dBm. So 5dB Attenuator is added Between MT6120 and
RF3146. Tx VCO Frequency Range is same with Tranceiver Frequency Range.
4.
Frequency Synthesizer
The MT6120 includes a frequency synthesizer with a fully integrated RF VCO to generate RX and TX
local oscillator frequencies. The PLL locks the RF VCO to a precision reference frequency at 26MHz.
To reduce the acquisition time or to enable fast settling time for multi-slot data services such as GPRS,
a digital loop along with a fast-acquisition system are implemented in the synthesizer. After the
calibration, a fast-acquisition system is utilized for a period of time to facilitate fast locking.
The frequency ranges of the synthesizer for RX mode are
RX mode GSM850
1737Mhz ~ 1788Mhz
E-GSM900
1850Mhz ~ 1920Mhz
DCS1800
1805Mhz ~ 1880Mhz
PCS1900
1930Mhz ~1990Mhz
The Calculate LO Freqnecy Fvco from RX Channel Frequency Fch is following.
Fvco = 2*Fch-200K
for GSM850
Fvco = Fch-100K
for PCSL599900.
The frequency ranges of the synthesizer for TX mode are
TX mode
GSM850
1813Mhz ~ 1868Mhz
E-GSM900
1936Mhz ~ 2059Mhz
DCS1800
1881Mhz ~ 2008Mhz
PCS1900
2035Mhz ~2149Mhz
The Calculate LO Freqnecy Fvco from TX Channel Frequency Fch is following.
(set the divider ratio D1 of TX reference divider = 11)
Fvco = 2*D1*Fch/(D1-1)
for GSM850
Fvco = D1*Fch/(D1-1)
for PCSL599900.
The MT6120 uses a digital calibration technique to reduce the PLL settling time Once the RF
synthesizer is programmed through a 3-wire serial interface, the calibration loop is activated. The main
