Circuit Description - Samsung SGH-Z140 Service Manual

2. Circuit Description

2-1. SGH-Z140 RF Circuit Description
- Antenna Switch Module (U103)
The antenna switch module allows multiple operating bands and modes to share the same antenna. A common
antenna connects to one of seven paths: 1) UMTS-2100 Rx/Tx, 2) EGSM-900 Rx, 3) EGSM-900 Tx, 4) DCS-1800
Rx, and 5) DCS-1800 Tx. 6) PCS-1900 Tx, 7) PCS-1900 Rx, UMTS operation requires simultaneous reception and
transmission.
- Filter
To convert Electromagnetic Field Wave to Acoustic Wave and then pass the specific frequency band.
· GSM Rx FILTER (F100) ¡ æ
· DCS Rx FILTER (F101) ¡ æ
· PCS Rx FILTER (F102) ¡ æ
· WCDMA Rx FILTER (F200) ¡ æ
· WCDMA Tx FILTER (F201) ¡ æ
- VCTCXO (OSC200)
To generate the 19.2MHz reference clock to drive the logic and RF.
- Duplexer (F203)
A duplexer splits a single operating band into receive and transmit paths.
- WCDMA PAM (U201)
This is a key component in the transmitter chain and must complement the RTR6200 IC precisely; jointly they
dominate the UMTS transmitter performance characteristics. Parameters such as gain, output power level, ACLR,
harmonics, Rx-band noise, and power supply current are critical.
- GSM/DCS PAM (U102)
The PAM is a key component in any transmitter chain and must complement the rest of the transmitter precisely.
For GSM, DCS, PCS operation, the closed-loop transmit power control functions add even more requirements relative
to the UMTS PA. In addition to gain control and switching requirements, the usual RF parameters such as gain,
output power level, several output spectrum requirements, and power supply current are critical.
- GSM/DCS Dual Tx VCO (OSC101)
The dual Tx VCO outputs, one for EGSM and one for DCS, drive a resistive network that splits the active signal
into two signals: 1) the input to the active PAM – this is the low loss path, and 2) the OPLL feedback signal.
- Dual VCO (OSC201)
The dual-band UHF VCO is a key component within its phase-locked loop; VCO performance directly impacts PLL
and transceiver performance. GSM/DCS Rx/Tx LO & UMTS Rx LO signal is generated from this dual VCO's output.
For filtering the frequency band between 925 ~ 960 MHz.
For filtering the frequency band 1805 and 1880 MHz.
For filtering the frequency band 1930 and 1990 MHz.
For filtering the frequency band 2110 and 2170 MHz.
For filtering the frequency band 1920 and 1980 MHz.
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