SAMSUNG Proprietary-Contents may change without notice
2. Circuit Description
This Document can not be used without Samsung's authorization
2-1
2-1. SGH-i750 RF Circuit Description
2-1-1. ANTENNA SWITCH (U101:LMG003S-5091A)
→
Switching Tx, Rx path for EGSM900, DCS1800 and PCS1900 by logic controlling.
<TruthTable>
2-1-2. FILTER
To convert Electromagnetic Field Wave to Acoustic Wave and then pass the specific frequency band.
- GSM FILTER (F101)
→
For filtering the frequency band between 925 and 960 MHz
- DCS FILTER (F103)
→
For filtering the frequency band between 1805 and 1880 MHz.
- PCS FILTER (F102)
→
For filtering the frequency band between 1930 and 1990 MHz.
2-1-3. TRANSCEIVER (U102:UAA3587EHN/C2)
This chip is fully integrated GSM GPRS quad-band transceiver with transmit baluns, 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 EGSM900, 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.
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 VC2 VC3
Tx Mode (GSM900) L H L
Tx Mode (DCS1800/1900) L L H
Rx Mode (GSM900) L L L
Rx Mode (DCS1800) L L L
Rx Mode (PCS1900) H L L
