LG VX8610 Service Manual page 29

VX8610
1.2 Description of RX Part Circuit
1.2.1 Diplexer (F101)
The main function of Diplexer is to prohibit the other band signals from flowing into the one band circuit and vice
versa. RF designer can use common tri-band antenna regardless of frequency band (800, 1575 and 1900 MHz). The
specification of VX8610 Diplexer is described below:
Frequency Range
Temperature Range
1.2.2 Duplexer (DP100, DP101)
The duplexer consists of the RX bandpass filter (BPF) and the TX BPF which has the function of separating TX and
RX signals in the full duplex system for using the common antenna. The TX part BPF is used to suppress noises and
spurious out of the TX frequency band. The RX BPF is used to receive only RX signal coming from the antenna,
which is usually called preselector. It's main function is to limit the bandwidth of spectrum reaching the LNA and
mixer, attenuate receiver spurious response and suppress local oscillator energy. As a result frequency sensitivity and
selectivity of mobile phone increase. The specification of VX8610 duplexer described below ;
PCS duplexer:
Pass Band
Insertion Loss
Return Loss
Attenuation
Cellular duplexer
Pass Band
Insertion Loss
Return Loss
Attenuation
Copyright © 2007 LG Electronics. Inc. All right reserved
Only for training and service purposes
Insertion Loss to
Common
Isolation
TX
1850~1910 MHz
3.5dB max
9.5dB min
43dB min (1930~1990MHz)
TX
824~849 MHz
2.1B max
10dB min
46dB min (869~894MHz)
Cellular
824 – 894 MHz 1850 – 1990 MHz
0.5 dB Max
(At +25 deg)
18 dB Min
(to PCS)
-30 to +85 deg
RX
1930~1990 MHz
3.0dB max
9.5dB min
52dB min
(1850~1910MHz)
RX
869~894 MHz
2.6dB max
9dB min
54dB min (824~849MHz)
- 28 -
PCS
0.6 dB Max
(At +25 deg)
18 dB Min
(to Cellular)
TX to RX (min)
54dB (1850~1910MHz)
45dB (1930~1990MHz)
TX to RX (min)
56dB (824~849MHz)
47dB (869~894MHz)
LGE Internal Use Only