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
49/52
SL599
T
ECHNICAL
M
ANUAL
function of the calibration loop is to preset the RF VCO to the vicinity of the desired frequency
quickly and correctly, thus aiding the PLL to settle faster. On the other hand, since a large portion of
initial frequency error is dealt with by the integrated calibration loop, the overall locking time can be
drastically reduced, irrespective of the desired frequency.
5.
Voltage Control Crystal Oscillator(VCXO)
VCXO consists of an amplifier, a buffer, and a programmable capacitor array. The VCXO provides the
MT6120 with a selectable reference frequency of either 13MHz or 26MHz. When VCXOFRQ pin is
high, Output Frequency is 26Mhz. When VCXOFRQ pin is low, Output Frequency is 13Mhz.
VCXOFRQ is High in SL599. The Amplifier is designed to be in series resonance with a standard
26Mhz crystal. The Crystal is connected from the Input pin XAL of Amplifier to ground through a
series load capacitance. The buffer provides a typical 600mVpp voltage swing. As an alternative, the
reference frequency can be provided by an external 26Mhz VCTCXO module. When Pin VCXOCXR
is tied to the VCCVCXO supply, the XTAL pin will accept an external signal. Furthermore, the
VCXO control pin can be tied to VCCVCXO to prevent the current leakage during the sleep mode
operation.
6.
Regulator
The MT6120 internal regulators provide low noise, stable, temperature and process independent
supply voltages to critical blocks in the transceiver. An internal P-channel MOSFET pass transistor is
used to achieve a low dropout voltage of less than 150mV in all regulators.
II. RF3146 ( GSM850, PCS Power Amplifier Module)
Figure 35. RF3146 Block Diagram
