Rx Front-End; Fig 19 Block Diagram Of Antenna Switch: Left Input Port (Antenna) And Right Output Ports Rx/Tx - Nokia NPL-4 Series Troubleshooting Instructions

NPL-4/5/RM-104
Troubleshooting Instructions
signal VANT3=1, whereas VANT1=VANT2=0.
• Signal paths from the antenna switch to the band filters:
GSM 850/900:RX1
• GSM1800: RX2
• GSM1900: RX3
The antenna switch has following typical insertion losses in Rx-mode from its input to
output ports:
• GSM 850/900: 1.3 dB
• GSM 1800: 1.6 dB
• GSM 1900: 1.6 dB
Figure 19: Block Diagram of Antenna Switch: Left Input Port (Antenna) and Right Output Ports Rx/Tx

Rx front-end

The RX front-end includes three SAW filters for GSM 850 [US-variant] or GSM 900 [EU-
variant] (Z808), and for both variants GSM1800 (Z807), and GSM1900 (Z806). GSM 850/
900 and GSM 1800 filters are matched to the corresponding LNA inputs of the RF ASIC
(N500) with differential matching network (LC-type). For GSM 1900 an external LNA
(V802) improves the noise figure of the receiver. For conversion of the unbalanced output
port to the balances input port of the RF ASIC the BALUN (T801) is applied, followed by a
differential matching network (LC-type). The SAW filters provide the wanted out-of-
band blocking immunity. They have one single-ended (unbalanced) input port and two
balanced output ports each.
The SAW filters have approximately 2.5 to 3.2 dB insertion losses. The LNA for the GSM
1900 band provides a gain of approximately 17 to 20 dB.
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GSM850 SAW filter (Z808) or
GSM900 SAW filter (Z808)
GSM1800 SAW filter (Z807)
GSM1900 SAW filter (Z806)
EGSM
LPF
GSM1800
GSM1900
HPF
Nokia Customer Care
RX
LPF
TX
RX
LPF
TX
Issue 2 05/05