– 5-1 –
5.1. RF Overview
5.1.1. RF Block Diagram
5.1.2. Functional Description
The dual-band receiver comprises mainly an RF transceiver IC and and Front-End module.
The transceiver (U101) contains a direct conversion receiver with DC offset calibration circuitry and the following circuit blocks:
8
EGSM900 and DCS1800 internal LNAs.
8
EGSM900 and DCS1800 down-conversion mixers/demodulators.
8
Channel filtering and base-band signal variable gain amplifiers with programmable gain control function.
The Antenna Switch Module S101 is a dual-band antenna switch module. Two external SAW filters EL201 and FL202 for
EGSM900 and DCS1800 are used to improve the isolation between 900MHz and 1800MHz.
The impedance of these two filters' output is 150
Ω
balanced.
EGSM900/DCS1800
The input receiving signals into the LNAs coming from the SAWs provide out-band reflection.
However, the receiver is a direct conversion type, there is no need to concern about the image frequency blocking problem.
Figure 5.1. RF Block Diagram
5. TECHNICAL DESCRIPTION
U301
TCXO module
MAA****A
26 MHz
I/IB
Q/QB
13M_BB
PALEVEL
AFC
EGSM900
925 - 960 MHz
EGSM900
880 - 915 MHz
DCS1800
1710 - 1785 MHz
U103
PA Module
RF3140
DCS1800
1805 - 1880 MHz
S101
Antenna Switch module
FL102
Tx SAW EGSM
EFCH897MMTE7
FL202
Rx SAW Filter EGSM
B7820
FL201
Rx SAW Filter DCS
B7821
U101
Transceiver IC
DC offset Compensation
1/4
+
+
U102
Tx Limiter IC
PMB2256V V1.1
TXON
CLK/DA/EN
BAND_SEL
RF Synth
PLLON
3420 - 3980 MHz
VC1
VC2
TXON_PA
AM_TRIG
TEMP
π
/2
1/4
π
/2
1/2
π
/2
1/2
π
/2
Summary of Contents for EB-X400
Page 86: ...12 1 12 LAYOUT DIAGRAMS 12 1 Main Board U2001 ...
Page 87: ...12 2 ...
Page 88: ...12 2 Upper Face PCB 12 3 Green Black Black White ...
Page 89: ...12 3 Hinge PCB 12 4 ...
Page 90: ...12 4 SIM PCB 12 5 ...