LG G5200 13 free download

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3. TECHNICAL BRIEF 3. TECHNICAL BRIEF 3.1 General Descreption The RF parts consists of a transmitter part,a receiver part,a synthesizer part,a voltage supply part,a VCTCXO part. And the main RF Chipset CX74017[U411]is a single-chip dual-band transceiver for the extended global system for mobile communication[E- GSM900MHz]/Digital communication system[DCS1800MHz] voice and data transfer applications. This device integrated a direct conversion receiver architecture, which eliminates the need of Intermediate Frequency, a transmitter based on a modulation loop architecture and fractional-N synthesizer part with built in TXVCO and Local-VCO. 3.2 Receiver Figure 3-1. RF front-end circuit. The Receiver part in CX74017 contains all active circuits completely, full receiver chain with the exception of discrete front-end RF SAW filters. The filtered and amplified signal is down converted in the RF-mixer to the baseband output. The receiver path is supported by internal channel filtering. The RF front-end circuit is shown Figure 3-1. - 13 - 3. TECHNICAL BRIEF A. RF front end RF front end consists of Antenna Switch(U405), dual band LNAs integrated in transceiver(U411). The Received RF signals (GSM 925MHz ~ 960MHz, DCS 1805MHz ~ 1880MHz) are fed into the antenna or mobile switch. An antenna matching circuit is between the antenna and the mobile switch. The Antenna Switch (U405) is used to control the Rx and TX paths. And, the input signals VC1 and VC2 of a U405 are connected to 2-Input AND Gates(U401) to switch either TX or RX path on. When the RX path is turned on, the received RF signal then feeds either Rx_900_RF or RX_1800_RF path selected by GSM-RX and DCS-RX respectively. This Rx_900_RF path contains one SAW filter, followed after the Antenna Switch (U405), to filter any unwanted signal apart from the DCS RX band. And, the RX_1800_RF path is the same case. The logic and current for Antenna Switch is given below Table 3-1. Table 3-1. The logic and current VC1 VC2 Current GSM TX 0V 2.7 V 10.0 mA max DCS TX 2.7 V 0V 10.0 mA max GSM/DCS RX 0V 0V < 0.1 mA These two paths are then connected to the LNAGSMN (#11) and LNADCSIN (#13) of CX74017 (U411), respectively. A low-noise bipolar RF amplifier, contained within the U411, amplifies the RF signal. The RF signals from the front-end pass to the receiver mixers within the U411 device. B. Demodulator and baseband processing In direct conversion receive