Samsung SGH-V206 Service Manual page 9

SG H- V206 Circuit Description
2) TX PART
Baseband IQ signal fed into offset PLL, this function is included inside of U902 chip.
SI4200 chip generates modulator signal which power level is about 1.5dBm and fed into Power Amplifier(U1008).
The PA output power and power ramping are well controlled by Auto
Power Control circuit. We use offset PLL below
Modulation Spectrum
2. Baseband Circuit description of SGH-V200
1. PSC2006
1.1. Power Management
Seven low-dropout regulators designed specifically for GSM applications power the terminal and help ensure optimal
system performance and long battery life. A programmable boost converter provides support for 1.8V, 3.0V, and 5.0V
SIMs, while a self-resetting, electronically fused switch supplies power to external accessories. Ancillary support functions,
such as an LED driver and two call-alert drivers, aid in reducing both board area and system complexity.
A three-wire serial interface unit(SIU) provides access to control and configuration registers. This interface gives a
microprocessor full control of the PSC2006 and enables system designers to maximize both standby and talk times.
Supervisory functions. including a reset generator, an input voltage monitor, and a thermal monitor, support reliable system
design. These functions work together to ensure proper system behavior during start-up or in the event of a fault
condition(low microprocessor voltage, insufficient battery energy, or excessive die temperature).
1.2. Battery Charge Management
A battery charge management block provides fast, efficient charging of a single-cell Li-ion battery. Used in conjunction
with a current-limited voltage source and an external PMOS pass transistor, this block safely conditions near-dead cells
and provides the option of having fast-charge and top-off controlled internally or by the system's microprocessor.
1.3. Backlight LED Driver
The backlight LED driver is a low-side, programmable current source designed to control the brightness of the keyboard
and LCD illumination. The driver is enabled by EN_LED, and its current setting is determined by LED[0:2]. Provided
EN_LED is ¡® 1 ¡¯ , the driver can be programmed to sink from 12.5mA to 100mA in 12.5mA steps. LED_DRV is
capable of sinking 100mA at a worst-case maximum output voltage of 0.6V. For efficient use, the LEDs is connected
between the battery and the LED_DRV output.
200kHz offset
30 kHz bandwidth
400kHz offset
30 kHz bandwidth
600kHz ~ 1.8MHz offset
30 kHz bandwidth
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GSM
DCS
PCS
GSM
DCS
PCS
GSM
DCS
PCS
4- 2
-35dBc
-35dBc
-35dBc
-66dBc
-65dBc
-66dBc
-75dBc
-68dBc
-75dBc