Circuit Description; General Description; Rf Part - LG L240 Service Manual

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3. Circuit Description

The RF part consists of a transmitter, a receiver, a synthesizer, a voltage supply and a VC-TCXO part.

The main RF Chipset MMM6000 is a transceiver for the GSM, GPRS, and EDGE standards, providing

antenna-todigital- bits functionality. The transceiver functions over the GSM850, EGSM900, DCS1800,

and PCS1900 transmit and receive frequency bands. The MMM6000 transceiver includes a VLIF/DCR

receive architecture and a polar modulation transmit architecture with direct modulation of the VCO by

a fractional-N synthesizer. Both the RX and TX VCOs are fully integrated. The polar architecture

allows for a filter-free transmit lineup. An on-chip transmit/receiver sequencer generates appropriate

timing events for the transmitter calibration and the EDGE / GMSK transmit/receive burst, therefore,

limiting the RF hardware dependency of the L1 engine software to an absolute minimum. The DigRF

standard defines the digital interface between the MMM6000 and the base band processor IC,

allowing maximum industry compatibility.

3.2.1 Receiver Part

The Receiver part in MMM6000 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 ba se-band output. The receive path is supported by internal channel filtering.

<Fig.1> Receiver Part Block Diagram

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