Nokia NHL-10 - Transmitter Troubleshooting; General Description

NHL-10
RF Troubleshooting CCS Technical Documentation
ISSUE 2 01/2004 COMPANY CONFIDENTIAL 25
Copyright © 2003 Nokia. All Rights Reserved.
Transmitter Troubleshooting
General Description
A simple block diagram of the TX part of the phone is shown in the following figure. The voice
or data signals to be transmitted come from the UEME IC in the BB (Base Band) area, and go
to the Mjølner IC, where they are up-converted to RF. The TX signals going from UEME to Mjøl-
ner are called the IQ signals, and consist of two balanced signals { TXIN, TXIP } and { TXQN,
TXQP }, i.e. a total of four signal lines. In addition to the IQ-signals, there are also control sig-
nals going between BB and RF.
Figure 1: TX RF Block Diagram
The picture below shows the two shielding cans where the TX circuitry is located (the lid has
been removed). The shielding can on the right side contains BB-RF interface circuitry, the Mjøl-
ner RF system IC, a SAW filter for the EGSM band, and a balun for the DCS/PCS band. The
shielding can on the left side contains the power amplifier (PA), the EGSM pre-amplifier, the
directional coupler, the power detector, and the Antenna Switch Module (ASM).
Mjølner
SAW
Discrete
TX buffer/amp
Coupler Ant-Switch
1800 / 1900MHz
900MHz
PA
Power
Detect
Power Loop Filter
From UEME:
TXIQ
TXC
4
BB-RF
Interface
Signals:
From UPP:
TXP
RFBUSCLK
RFBUSEN1
RFBUSDA
RESET
VPD_900
VPD_1800
2
DET
VBD (DIODE BIAS)
VTXB_900 (BUFFER BIAS)
V_BAT
1/4
1/2
LO
2
4
4
Synthesizer
(LO=Local Oscillator)