User Guide

RAE-6/RA-4

Nokia Customer Care 6 - Baseband Description and Troubleshooting

12 COMPANY CONFIDENTIAL Issue 1 12/04

Functional Description of CMT

The CMT architecture of RAE-6/RA-4 is based on DCT4 Common Baseband. The main func-

tionality of the CMT baseband is implemented into two ASICs: UPP (Universal Phone Proces-

sor) and UEMEK (Universal Energy Management).

32Mbit NOR flash is used to store the program code. For a simplified block diagram of the RAE-

6/RA-4 CMT baseband, see Figure 2, “Simplified CMT baseband block diagram” on page 13.

System clock for the CMT is derived from the RF circuits. For GSM it is 26 MHz. The low fre-

quency sleep clock is generated in the UEMEK using an external 32.768 kHz crystal. The I/O

voltage of the CMT baseband is 1.8V and the analog parts are powered from 2.8V power rails.

The core voltage of UPP can be altered with SW depending on the prevailing processing power

requirements.

UEMEK is a dual voltage circuit. The digital parts are running from the baseband supply (1.8V)

and the analog parts are running from the analog supply (2.8V). Some blocks of UEMEK are

also connected directly to the battery voltage (VBAT). UEMEK includes 6 linear LDO (low drop-

out) regulator for the baseband and 7 regulators for the RF. It also includes 4 current sources

for biasing purposes and internal usage.

Some parts of the SIM interface have been integrated into UEMEK. The SIM interface supports

only 1.8V and 3V SIM cards. Data transmission between the UEMEK and UPP is handled via

two serial buses: DBUS for DSP and CBUS for MCU. There are also separate signals for PDM

coded audio. Digital speech processing is handled by the DSP inside UPP and the audio codec

is in UEMEK.

The analog interface between the baseband and the RF sections has been implemented into

UEMEK. UEMEK provides A/D and D/A conversion of the in-phase and quadrature receive and

transmit signal paths and supplies the analog TXC and AFC signals to RF section under the

UPP DSP control. The digital RF-BB interface, consisting of a dedicated RFIC control bus and

a group of GenIO pins, is located in the UPP.

The baseband side supports both internal and external microphone inputs and speaker out-

puts. Input and output signal source selection and gain control is performed in the UEMEK ac-

cording to control messages from the UPP. Keypad tones, DTMF, and other audio tones are

generated and encoded by the UPP and transmitted to UEMEK for decoding.

RAE-6/RA-4 has two galvanic serial control interfaces for CMT: FBUS and MBUS.

Communication between the APE and CMT parts is handled through 2 serial buses: XBUS and

XABUS. XBUS is the main communication channel for general use, and XABUS is intended

mainly for audio data transfer. Also the system reset (PURX) and SleepClk for APE are taken

from the CMT side. The PURX is delayed approximately 130ms to fulfil OMAP1510 reset timing

requirements. External level shifter, D4801, is used for 32 kHz SleepClk level shifting to APE.