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Circuit Description
2-2
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B. TX PART
Baseband IQ signal fed into offset PLL, this function is included inside of U100 chip.
UAA3536 chip generates modulator signal which power level is about 1.5dBm and fed into
Power Amplifier(U105).
The PA output power and power ramping are well controlled by Auto Power Control circuit.
We use offset PLL below table.
Modulation Spectrum
200kHz offset
30 kHz bandwidth
GSM
-35dBc
DCS
-35dBc
400kHz offset
30 kHz bandwidth
GSM
-66dBc
DCS
-65dBc
600kHz ~ 1.8MHz offset
30 kHz bandwidth
GSM
-75dBc
DCS
-68dBc
Ⅱ
. Baseband Circuit description of SGH-X460
A. PCF50601
1. Power Management
Ten 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 RTC module
and High Voltage Charge pump, Clock generator, aid in reducing both board area and system
complexity.
I2C BUS serial interface provides access to control and configuration registers. This interface
gives a microprocessor full control of the PCF50601 and enables system designers to maximize
both standby and talk times.
Supervisory functions. including a reset generator, an input voltage monitor, and a temperature
sensor, 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).
2. Backlight Brightness Modulator
The Backlight Brightness Modulator (BBM) contains a programmable Pulse-width modulator
(PWM) and FET to modulate the intensity of a series of LED’s or to control a DC/DC
converter that drives LCD backlight.
This phone (SGH-X460) use PWM.