Panasonic EB-G60 Service Manual page 25

The CX74017 transceiver is a highly integrated device for multi-band Global System for Mobile Communications™ (GSM ™)
or General Packet Radio Service (GPRS) applications. The device requires a minimal number of external components to
complete a GSM radio subsystem. The CX74017 supports EGSM900/DCS1800 applications.
The receive path implements a direct down-conversion architecture that eliminates the need for Intermediate Frequency (IF)
components. The CX74017 receiver consists of three integrated Low Noise Amplifiers (LNAs), a quadrature demodulator,
tunable receiver baseband filters, and a DC-offset correction sequencer.
In the transmit path, the device consists of an In-phase and Quadrature (I/Q) modulator within a frequency translation loop
designed to perform frequency up conversion with high output spectral purity. This loop also contains a phase frequency
detector, charge pump, mixer, programmable dividers, and high power transmit Voltage Controlled Oscillators (VCOs) with no
external tank required.
The charge pump output signal produced by the phase detector is fed back to the Tx VCO to generate modulated RF output.
The Tx VCO has been designed to provide a high level output thus obviating the need for a driver amplifier. Therefore, the Tx
VCO output is applied directly to the PA which amplifies the signal to any required level up to PL5 (33 dBm at the antenna) for
E-GSM 900 and PL0 (30 dBm) for GSM 1800. In the same way, the Tx VCO output is applied directly to the PA which
amplifies the signal to any required level up to PL5 (33 dBm at the antenna) for GSM 850 and PL0 (30 dBm) for GSM 1900.
The CX74017 also features an integrated, fully programmable, sigma-delta fractional-N synthesizer suitable for GPRS
multi-slot operation. Except for the loop filter, the frequency synthesizer function, including a wideband VCO, is completely
on-chip.
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