Transcript 2004 GSM

Galaxy H/W Training
- GPRS RF Part
ASUS RD Division
IA Department HW-2 Group
Alan Lin
2006/01/23
Agenda
• Introduce to GPRS Function
- Block Diagram
- Key Parts List
- Aero II Architecture Highlights
- Transmitter
- Receiver
• Trouble Shooting
- Ckt. & Location
- AFC
- APC
- AGC
2
Introduce to GPRS Function
GPRS Block Diagram
PMIC
Analog IQ
T/R SW
RF Chip
BB Chip
Flash
BB Part
PA
RF Part
FFUART
Pink : GPRS RF
Green : GPRS Base-Band
Blue : PDA
PDA Part
4
Transceiver Block Diagram
850: 856441
1800: 856409
900: 856387
1900: 856417
LMSP33QA-321
RF3166
5
Base-band Block Diagram
Audio RX path
Analog IQ
signal
Audio TX path
3 wire bus for
RF transceiver
SIM
RF Control T/R
switch
6
Key Parts List
7
Aero II RX Highlights
• Low IF architecture strengths (200kHz IF)
– Has advantages of Super-Heterodyne architectures :
– DC Offsets are located outside the band of interest.
– IP2 (AM Suppression) requirements are relaxed.
– LO Self Mixing is not a problem.
– Has advantages of Direct Conversion architectures :
– No IF SAW Filter required – Image Rejection
requirements are simplified.
– Single analog down-conversion stage.
– IF Analog Signal Processing is at a low frequency.
– Digital IF signal processing.
8
Transceiver Functional Block
Universal Baseband Interface
RX Loop
RX SAW
(DAC)
Power Amp.
TX Loop
Synthesizer
XTAL(DCXO)
9
Receiver Block Diagram
Image Reject
Low - IF Receiver
10
Low-IF Receiver
11
Image Rejection
12
Aero II TX Highlights
• Offset PLL architecture
– Band Pass Noise Transfer Function attenuates noise in
RX band.
– TXVCO is a constant-envelope signal that reduces the
problem of spectral spreading caused by non-linearity
in the PA.
– Eliminates need for TX SAW Filter.
• TX transmit out buffer
– Helps eliminate spurs and pulling issues.
13
Transmitter Block Diagram
Offset PLL
14
Offset PLL
- The OPLL acts as a tracking band-pass filter tuned to the
desired channel frequency.
- The important difference between a PLL and the OPLL is
that the frequency modulation of the reference input is
reproduced at the output of the Tx-VCO without scaling
• Advantage
- Low noise floor and spurs
- Pulling of the transmit
VCO is reduced
-Truly constant envelope
Output from VCO
• Disadvantage
- Only possible with constant
envelope modulation scheme
15
DCXO Architecture
Frequency adjusted by two variable capacitances
- Cdac: coarse tuning
- Cafc: fine tuning
16
Trouble Shooting
Measurement Equipment
Phone Tool
GSM tester
I
•
•
•
•
•
Q
Data cable
Spectrum Analyzer
RF adaptor
RF
DUT
Agilent 8960 / CMU200
Power Supply
Scope
Spectrum
Passive Probe with DC Block
Oscilloscope
18
Base Station Setup
•
Base Station Test Mode Setup
GSM850
EGSM
DCS
PCS
Mode
BCH + TCH
BCH + TCH
BCH + TCH
BCH + TCH
BS Power -60dBm, -20dBm -60dBm, -20dBm -60dBm, -20dBm -60dBm, -20dBm
BCH
190
62
700
661
TCH
190
62
700
661
TX PCL
5, 19
5, 19
0, 15
0, 15
19
Antenna Switch Connector
Bottom Side
Antenna Switch Connector
20
PA & Front-end
Top Side
T/R Switch
Low band Matching
High band Matching
PA
21
PA & Front-end
Low band
Matching
PA
High band
Matching
PALEVEL
(VRAMP)
T/R Switching
22
RX Path
Top Side
XTAL
Transceiver
RX SAW
T/R Switch
23
RX Path
T/R Switching
RX SAW
Transceiver
RX SAW
XTAL
24
T/R Control Table
25
Trouble Shooting
•
•
•
•
•
AFC Fail
APC Fail
AGC Fail
ORFS due to Modulation Fail
@ -200kHz & +400kHz fail
Others
26
AFC & TX Testing Nodes
A
F
D
B
E
G
C
H
27
AFC Fail
• Check antenna switch connector
• Check Vramp & PA output power
• Check 26MHz output
PA
28
APC Fail
•
If TX current is right
- Check antenna switch connector
- Check T/R switch
- Check PA matching circuit
T/R SW
High-band out
Low-band out
High-band in
Low-band in
Vramp
29
APC Fail
•
If TX current is small
- Check TXVCO output
- Check Vramp
- Check PA
- Check VBAT
T/R SW
High-band out
Low-band out
High-band in
Low-band in
Vramp
30
AFC & TX Signals
Node
A
B
C
D
E
F
Description
XOUT at C957
TXIQ
TXVCO at C947(GSM850/EGSM)
TXVCO at C944 (DCS/PCS)
Power at T/RSW(C930) Low-band in
Power at T/RSW(C933) High-band in
G
Power at C946
H
Vramp
Value
26MHz, 1.6V
4.6ms, 1.2V(max)
PCL : 19, 902.4MHz
PCL : 15, 1747.8MHz
PCL : 19, 902.4MHz
PCL : 15, 1747.8MHz
PCL : 19, 902.4MHz
PCL : 15, 1747.8MHz
EGSM : 1.3V (PCL5), 0.3V (PCL19)
DCS : 1.28V (PCL0), 0.3V (PCL15)
Fig.
1.1
1.2
ref. 1.3
1.3
ref. 1.4
1.4
1.4
1.5
31
26MHz & TXIQ
Fig. 1.1 26MHz
Fig. 1.2 TXIQ
32
TXVCO
Fig. 1.3 TXVCO DCS Ch700 : 1747.8MHz
Fig. 1.4 PA Out DCS Ch700 : 1747.8MHz
33
Vramp
Fig. 1.5 Vramp
34
RX Testing Nodes
F
A
E
D
C
B
35
AGC Fail
•
•
•
•
Check
Check
Check
Check
antenna switch connector
T/R switch
SAW
RXIQ
RX SAW
36
RX Signals
Node
A
B
C
D
E
F
Description
XOUT at C957
Power at C946
Power at EGSM SAW out
Power at DCS SAW out
Power at PCS SAW out
RXIQ
Value
26MHz, 1.6V
EGSM Ch62 : 947.4MHz, BS: -20dBm
EGSM Ch62 : 947.4MHz, BS: -20dBm
DCS Ch700 : 1842.8MHz, BS: -20dBm
PCS Ch661 : 1960MHz, BS: -20dBm
EGSM Ch62 : 947.4MHz, BS: -20dBm
Fig.
2.1
ref. 2.2
2.2
ref.2.2
ref.2.2
2.3
37
26MHz & T/R Switch Out
Fig. 2.1 26MHz
Fig. 2.2 EGSM Ch62 : 947.4MHz
38
RX IQ
Fig. 2.5 RX IQ
39