LG ID2750 Service Manual page 21

LG-ID2750
The specifications of ID2750 LNA are described below
Parameter Gain Mode 0(G0) Gain Mode 1(G1) Gain Mode 2(G2) Gain Mode 3(G3) Unit
Gain 16
Noise Figure 1.5
Input IP3 10
1.2.3 Rx RF SAW FILTER (F101)
The main function of Rx RF SAW filter is to attenuate mobile phone spurious frequency, attenuate
noise amplified by the LNA and suppress second harmonic originating in the LNA.
1.2.4 Down-Converter Mixers (U104)
The RFR6122 device performs signal direct-down-conversion for Cellular applications. It contains all
the circuitry (with the exception of external filters) needed to support conversion of received RF
signals to baseband signals. The LO Buffer Amplifier buffers the RF VCO to the RF Transmit
Upconverter. RFR6122 offers the most advanced and integrated CDMA Rx solution designed to meet
cascaded Noise Figure (NF) and ThiID-oIDer Intercept Point (IIP3) requirements of IS-98C and
J-STD-018 specifications for Sensitivity, Two-Tone Intermodulation, and Single-tone Desense.
Operation modes and band selection are specially controlled from the Mobile Station Modem MSM6000.
The specification of ID2750 Mixers are described below:
Parameter
Noise Figure
Input IP3
Input IP2
1.3 Description of Transmit Part Circuit
1.3.1 Description on the Internal Circuit of MSM6000 (U201) and RFT6122 (U103)
For the transmit data path(Tx), the MSM6000 modulates, interpolates, and converts the digital signal
into an analog baseband before sending it to the RFT6122. The RFT6122 upconverts the Tx analog
baseband into RF. The MSM6000 communicates with the external RF and analog baseband to control
signal gain in the RF Rx and Tx signal paths, educe base band offset errors, and tune the system
frequency reference.
LGE
LG Electronics Inc.
4
5
7
High Gain Mode
10
4
56
19/26
-5 -20
5.5 20
15 15
Low Gain Mode Unit
25 dB
0 dBm
30 dBm
dB
dB
dBm