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LGE Internal Use Only
Copyright © 2009 LG Electronics. Inc. All right reserved.
Only for training and service purposes
4. RF Circuit Technical Brief
GW520 service manual
TX Output Power
The voltage at the VGA control pin TXGC (VGC) should be limited to ensure that the specified
maximum output power (minimum Poutmax) is not exceeded. The VGC value at which the specified
minimum Poutmax is reached varies from device to device. ACLR and other specifications are only
valid for output power levels below the specified minimum Poutmax.
TX Front End
An external power amplifier as well as duplex and interstage filters are needed to form a complete
transmit chain for each band.
4.3.3 Synthesizer
The receiver and the transmitter contain each a complete fractional-N RF synthesizer with fast locking.
The VCO’s run at 4 GHz and the RX and TX frequencies are obtained through division by two (bands I,
II, III and IV) or four (bands V and VI). The PLL loop filters are fully integrated. The reference
frequency has to be provided by an external clock.
The total VCO frequency range is divided in 256 subranges, in order to limit the VCO slope. Before the
settling process of the PLL starts, a successive approximation algorithm selects the most appropriate
subrange.
Содержание GW520
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