Samsung Z540 Service Manual

2. Circuit Description

2-1. SGH-Z540 RF Circuit Description

1. Antenna Switch Module (U702)
The antenna switch module allows multiple operating bands and modes to share the same antenna. A common
antenna connects to one of five 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.

2. Filter
To convert Electromagnetic Field Wave to Acoustic Wave and then pass the specific frequency band.

- GSM Rx FILTER (F702)→For filtering the frequency band between 925 ~ 960 MHz.

- DCS Rx FILTER (F701)→For filtering the frequency band 1805 and 1880 MHz.

- PCS Rx FILTER (F700)→For filtering the frequency band 1930 and 1990 MHz.

- WCDMA Rx FILTER (F800)→For filtering the frequency band 2110 and 2170 MHz.

- WCDMA Tx FILTER (F802)→For filtering the frequency band 1920 and 1980 MHz.

3. VCTCXO
To generate the 19.2MHz reference clock to drive the logic and RF.

4. Duplexer (TCX800)
A duplexer splits a single operating band into receive and transmit paths.

5. UMTS PAM (U800)
This is a key component in the transmitter chain and must complement the RTR6250 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.

6. GSM/DCS/PCS PAM (U701)
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.

7. GSM/DCS/PCS l Tx VCO (OSC700)
The Tx VCO outputs for EGSM, DCS, PCS 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.

8. RF VCO
The single-band UHF VCO is a key component within its phase-locked loop; VCO performance directly impacts
PLL and transceiver performance. UMTS Rx LO signal is generated from this VCO's output.

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Circuit Description

9. RFR6250 (U801)
The RFR6250 provides the Zero-IF receiver signal path, from RF to analog baseband, for UMTS-2100
applications. The RFR6250 accepts its UMTS input signal from the handset RF front-end design. The UMTS input
is configured differentially to optimize second-order inter-modulation and common mode rejection performance, and
implements MSM-controlled gain adjustments to extend the receiver dynamic range.

10. RTR6250 (UCD700)
The RTR6250 supports multi-band, multi-mode phones with two receiver signal paths and three transmitter signal
paths:

1) Receiver paths

- EGSM-900

-DCS-1800

- PCS-1900

2) Transmitter paths

- EGSM-900 (using OPLL technique)

- DCS-1800 (using OPLL technique)

- PCS-1900

- UMTS-2100
Numerous secondary functions are integrated on-chip as well:

3) Phase-locked loop circuits

- PLL#1 and an on-chip VCO supports UMTS Tx

- PLL#2 and an external VCO supports EGSM Rx and Tx, DCS Rx and Tx, and UMTS Rx

4) Transceiver LO generation and distribution circuits

- EGSM-900 Rx and Tx

- DCS-1800 Rx and Tx

- UMTS-2100 Tx

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