Baseband Module; Technical Summary - Nokia Mobile Phones NSE-5 Series Service Manual

PAMS
Technical Documentation

Baseband Module

Technical Summary

The baseband architecture is basically similar to DCT3 GSM phones.
DCT3.5 differs from DCT3 in the single pcb koncept and the seriel
interface between MAD2PR1 and COBBA_GJP and MAD2PR1 and
CCONT. In DCT3.5 the MCU, the system specific ASIC and the DSP are
intergrated into one ASIC, called the MAD2PR1 chip, which takes care of
all the signal processing and operation controlling tasks of the phone.
The baseband architecture supports a power saving function called "sleep
mode". This sleep mode shuts off the VCTCXO, which is used as system
clock source for both RF and baseband. During the sleep mode the
system runs from a 32 kHz crystal. The phone is waken up by a timer
running from this 32 kHz clock supply. The sleeping time is determined by
some network parameters. When the sleep mode is entered both the
MCU and the DSP are in standby mode and the normal VCTCXO clock
has been switched off.
The battery voltage range in DCT3 family is 3.0V to 4.5V depending on
the battery charge and used cell type (Li–Ion or NiMH). Because of the
lower battery voltage the baseband supply voltage is lowered to a nominal
of 2.8V.
The baseband is running from a 2.8V power rail which is supplied by a
power controling asic (CCONT). In the CCONT there are seven
individually controlled regulator outputs for the RF section, one 2.8V
output for the baseband plus a core voltage for MAD2PR1. However this
is not used in NSE–5 because the chipset supports 2.8Volts. In addition
there is one +5V power supply output(V5V). TheCCONTalso contains a
SIM interface which supports both 3V and 5V SIM cards. A real time clock
function is integrated into the CCONT which utilises the same 32KHz
clock supply as the sleep clock. A backup power supply is provided for
the RTC which keeps the real time clock running when the main battery is
removed. The backup power supply is a rechargeable polyacene battery
with a backup time of ten minutes.
The interface between the baseband and the RF section is handled by a
specific asic. The COBBA_GJP asic provides 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 parts. Data transmission between the COBBA_GJP and the
MAD2PR1 is implemented using serial connections. Digital speech
processing is handled by the MAD2PR1 asic. The COBBA_GJP asic is a
dual supply voltage circuit, the digital parts are running from the baseband
supply VBB and the analog parts are running from the analog supply
VCOBBA (VR6).
Issue 1 07/99
NSE–5
System Module
Page 2 – 17