NSB–6
System Module
PAMS Technical Documentation
Page 9
Issue 1 06/2000
E
Nokia Mobile Phones Ltd.
Technical Summary
The baseband module consists four ASICs; CHAPS, CCONT, COBBA–
GJP and MAD2WD1, which take care of the baseband functions of the
engine.
The baseband is running from a 2.8V power rail, which is supplied by a
power controlling ASIC CCONT. MAD2WD1 supply voltages are VBB and
VCORE (V2V), VBB feeds I/O pins so that MAD2WD1 is externally fully
compatible with old versions. VCORE feeds MAD2WD1 internal fuctions
supplyoltage; CPU, DSP and system logic. In the CCONT there are 6 in-
dividually controlled regulator outputs for RF–section and two outputs for
the baseband. In addition there is one +5V power supply output (V5V).
The CCONT contains also a SIM interface, which supports both 3V and
5V SIM–cards. A real time clock function is integrated into the CCONT,
which utilizes 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
rechargable battery. The backup time with the battery is ten minutes mini-
mum.
The interface between the baseband and the RF section is mainly han-
dled by a COBBA ASIC. COBBA 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 user interface. The COBBA supplies the analog TXC and AFC
signals to RF section according to the MAD DSP digital control. Data
transmission between the COBBA and the MAD is implemented using se-
rial bus for high speed signalling and for PCM coded audio signals. Digital
speech processing is handled by the MAD ASIC. COBBA is a dual volt-
age circuit, the digital parts are running from the baseband supply VBB
and the analog parts are running from the analog supply VCOBBA.
The baseband supports both internal and external microphone inputs and
speaker outputs. Input and output signal source selection and gain control
is done by the COBBA according to control messages from the MAD.
Keypad tones, DTMF, and other audio tones are generated and encoded
by the MAD and transmitted to the COBBA for decoding. A buzzer and an
external vibra alert control signals are generated by the MAD with sepa-
rate PWM outputs.
EMC shielding is implemented using a metallized plastic frame. On the
other side the engine is shielded with PCB grounding. Heat generated by
the circuitry will be conducted out via the PCB ground planes.
