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2. Circuit Description
2-1. SGH-X670 RF Circuit Description
2-1-1. RX PART
- ANTENNA SWITCH (F101 Front End Module)
→ Switching Tx, Rx path for GSM900, DCS1800 and PCS1900 by logic controlling.
- ANTENNA SWITCH Control Losic (F101) → Truth Table
Tx Mode (GSM900)
Tx Mode (DCS1800/1900)
Rx Mode (GSM900)
Rx Mode (DCS1800)
Rx Mode (PCS1900)
- TRANSCEIVER (U102)
This chip is fully integrated GSM GPRS tri-band transceiver with transmit baluns(balanced-unbalanced matching devices) ,
loop filters and most of the passive component in it.
And also fully integrated fractional N RF synthesizer with AFC control possibility, RF VCO with integrated supply
regulator. Semi integrated reference oscillator with integrated supply regulator.
RF Receiver front-end amplifies the E-GSM900, DCS1800 and PCS1900 aerial signal, convert the chosen channel
down to a low IF of 100kHz.
In IF section, further amplifies the wanted channel output level to the desired value and rejects DC.
-PAM(PAM101)
The module consists of two separated line-ups, one for low band(LB 850/900) and one for high band(HB,1800/1900) with
input and output matching and internal power detection function and power control loop in GSM mode.
in GSM mode, the internal power control circuit ensures a stable power output, set by the level of V
compensate variations of supply voltage, input power and temperature, with a control range fully compaliant with ETSI
tome mask and power spectrum requirements
in EDGE mode the output power is controlled by the input power. The V
controlling the quiescent current of the final RF-statges of both line-ups.
2-1-2. TX PART
The transmitter is fully differential using a direct up conversion architecture. It consists of a signal side band
power up mixer. Gain is controlled by 6 dB via 3-wire serial bus programing. The fully integrated VCO and power
mixer achieve LO suppression, quadrature phase error, quadrature amplitude balance and low noise floor specification.
Output matching/balun components drive a standard 50 ohms single ended load.
VC1
H
L
L
L
L
SAMSUNG Proprietary-Contents may change without notice
This Document can not be used without Samsung's authorization
VC2
L
H
L
L
L
signal is used to control the efficiency by
REF
2-1
VC3
L
L(H)
L
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H
stabilsed to
DAC
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