Technical Summary - Nokia NSB-7 Series Service Manual

PAMS Technical Documentation

Technical Summary

The baseband module consists of 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 feed I/O pins so
that MAD2WD1 is externally fully compatible with old versions. VCORE feed MAD2WD1
internal functions supply voltage; CPU, DSP and system logic. In the CCONT there are 6
individually controlled regulator outputs for RF-section and two outputs for the base-
band. 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 minimum.
The analog interface between the baseband and the RF section is handled 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 serial bus for high speed signal-
ling and for PCM coded audio signals. Digital speech processing is handled by the MAD
ASIC. COBBA is a dual voltage 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 out-
puts. 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.
Issue 1 06/00 ãNokia Mobile Phones Ltd.
NSB-7
System Module
Page 9