Gsm Pa (U800) - Motorola V975 Service Manual

Service Manual(Level 3)

GSM PA (U800)

The TX VCO output signal from the ALGAE MB is
injected in the Durango 9E3G via the TX_OUT_LO
(Low Band) and TX_OUT_HI (Hi Band). Durango
Figure 3-9. Durango 9E3G (U800)
GSM PA
(U800)
9E3G is a quad band PA Module for GSM applica-
tions in 3G phones. The module uses a dual amplifier
lineup which operates in the three separate EGSM,
DCS1800, and PCS1900 bands. It is compatible with
GSM/GPRS operating modes. The integrated module
incorporates coupler/detector for power control, Low
pass filtering for harmonic rejection, and is internally
input and output matched to 50 ohms.
This Transmit module is to be used as the final amplifi-
cation stages in the A1000 for the EGSM (900 MHz),
DCS (1800 MHz) and PCS (1900 MHz).
The nominal expected maximum gain is ~30dB.
The VDET (output) is the RF feedback along the DC
reference V_REF_DET (output) are used in backend
PA Control (PAC) processing by the HARMONY.
VBA_1 and VBA_2 are inputs from HARMONY that
Draft 1.0 Motorola Confidential Proprietary
controls the PA output level. The voltage applied at the
pin is proportionally related to the output power of the
PA, as the voltage increases the gain or power level
increases.
The power detector is internal to the PA and is shared
among all GSM bands as well as WCDMA.
WB_VDET connects WCDMA TX to the power de-
tector
HB_EN enables the high band (DCS/PCS) amplifier
lineup. LB_EN enables the low band (EGSM) ampli-
fier lineup. TX_EN_2V7 enables the detector.
9E_VMODE sets the operating mode of the PA.
GMSK and EDGE modes are supported, but only
GMSK mode is used in this design. 9E_VMODE is set
high during GMSK TX mode. 9E-VMODE is set low
when the transmitter is in standby mode. This line is
also enabled in WCDMA mode to allow proper
WCDMA power detection.
Theory of Operation
RF GSM Transmitter
3-7