User Guide

Nokia Customer Care System Module
Company Confidential RH-21
Issue 2 07/2004  2004 Nokia Corporation. Page 9
VR3 regulator supplies VCTCXO and Safari in RF. It's always enabled when UEM is active.
When UEM is in sleep mode, VR3 is disabled.
VR4 regulator supplies RF parts having low noise requirements. In light load situations,
VR4 regulator can be set to low Iq-mode.
VR5 regulator supplies lower band PA. In light load situations, VR5 regulator can be set
to low Iq-mode.
VR6 regulator supplies higher band PA and TX amplifier. In light load situations, VR6 reg-
ulator can be set to low Iq-mode.
VR7 regulator supplies VCO and Safari. In light load situations, the VR7 regulator can be
set to low Iq-mode.
IPA1 and IPA2 are programmable current generators. 27kW/1%/100ppm external resistor
is used to improve the accuracy of output current. IPA1 is used by lower band PA and
IPA2 is used by higher band PA.
RF Interface
The interface between the baseband and the RF section also is handled by UEM. It pro-
vides A/D and D/A conversion of the in-phase and quadrature receive and transmit signal
paths and also A/D and D/A conversions of received and transmitted audio signals to and
from the UI section. The UEM supplies the analog AFC signal to RF section according to
the UPP DSP digital control. It also converts PA & VCTCXO temperature into real data for
the DSP.
Charging Control
The CHACON block of UEM asics controls charging. Needed functions for charging con-
trols are pwm-controlled battery charging switch, charger-monitoring circuitry, and bat-
tery voltage monitoring circuitry. In addition, external components are needed for EMC
protection of the charger input to the baseband module. The DCT4 baseband is designed
to support both DCT3 and DCT4 chargers from an electrical point of view.
Digital Interface
Data transmission between the UEM and the UPP is implemented using two serial con-
nections, DBUS (programmable clock) for DSP and CBUS (1.0MHz GSM and 1.08MHz
TDMA) for MCU. UEM is a dual voltage circuit, the digital parts are running from 1.8V
and the analog parts are running from 2.78V. Vbat (3,6V) voltage regulator inputs also
are used.
Audio Codec
The baseband supports two external microphone inputs and one external earphone out-
put. The inputs can be taken from an internal microphone, from a headset microphone,
or from an external microphone signal source through headset connector. The output for
the internal earpiece is a dual-ended type output, and the differential output is capable
of driving 4Vpp to the earpiece with a 60 dB minimum signal to total distortion ratio.
Input and output signal source selection and gain control is performed inside the UEM