Siemens SXG 75 Service Repair Documentation page 31

RTR6250 GSM / WCDMA Rx IQ Interface
RX0_I_M
RX0_I_P
RX0_Q_M
RX0_Q_P
RTR6250 / RFR6250 Serial Comms Interface
SBST_0
SBDT_0
SBCK_0
Antenna Switch Module Interface
ANT_SEL0
ANT_SEL1
ANT_SEL2
Antenna Position Sensor
ANT_POSN
PA temperature sensor
PA_THERM
TCXO control
TRK_LO_ADJ
RF interface signals
Technical Documentation
TD_Repair_L3_SXG75_R1.0.pdf
Received GSM and WCDMA IQ signals. The IQ signals are concerted to
digital by analog-to-digital converter (ADC) circuits within the MSM6250
IC.
The RTR6250 and RFR6250 operating modes and circuit parameters are
MSM-controlled through the proprietary 3-line serial bus interface.
The serial bus strobe signal is used by the MSM6250 to initiate serial data
transfers.
The serial bus data line is a bi-directional data line that transfers data into
and out of the ICs. All ICs configure this line as a tri-state driver for output
functions and as a CMOS gate for input functions. No external pull-up
resistor is needed.
The serial bus clock synchronizes data transfers.
Logic controls. ANT_SEL0=0, ANT_SEL1=0, ANT_SEL2=1 >
GSM900TX, ANT_SEL0=0, ANT_SEL1=0, ANT_SEL2=0 >
GSM900RX/WCDMA, ANT_SEL0=1, ANT_SEL1=1, ANT_SEL2=0 >
GSM1800/1900TX.
ANT_SEL0=0, ANT_SEL1=1, ANT_SEL2=0 > GSM1800RX.
ANT_SEL0=1, ANT_SEL1=0, ANT_SEL2=0 > GSM1900RX.
Logic signal to MSM6250. This line is pulled high when an external
antenna is fitted.
Voltage proportional to PA temperature from thermistor circuit
(R734/R732). Fed to HKAIN3 input to MSM6250 ADC multiplexer.
A pulse-density modulated digital signal from the MSM6250. It is filtered
by R900/C901 to form an analogue control voltage. The analogue voltage
is used to adjust the operating frequency of the TCXO.
Company Confidential
2006©BenQ
Release 1.0
01/2006
Page 31 of 73