LG LG-UD90c, Service Manual

Page: 16 / 88

LG-KG90C
16
1.3 Description of Frequency Synthesizer Circuit
1.3.1 Temperature Compensated Crystal Oscillator (TCXO, X1100)
Operating temperature is -30~+85
°
C. The receives frequency tuning signals called TRK_LO_ADJ
from MSM as 2.66V~2.94V DC via R and C filter in order to generate the reference frequency of 19.2
MHz and input it into the frequency synthesizer. Frequency stability depending on temperature is
±
2.0 ppm.
2. Digital/Voice Processing Part
2.1 Overview
The digital/voice processing part processes the user's commands and processes all the digital and
voice signal processing in order to operate in the phone. The digital/voice processing part is made up
of a keypad/LCD, receptacle part, voice processing part, mobile station modem part, memory part,
and power supply part.
2.2 Configuration
2.2.1 Keypad/LCD and Receptacle Part
This is used to transmit keypad signals to MSM6100. It is made up of a keypad backlight part that
illuminates the keypad, LCD part that displays the operation status onto the screen, and a receptacle
that receives and sends out voice and data with external sources.
2.2.2 Voice Processing Part
The voice processing part is made up of an audio codec used to convert MIC signals into digital voice
signals and digital voice signals into analog voice signals, amplifying part for amplifying the voice
signals and sending them to the ear piece, amplifying part that amplifies ringer signals coming out
from MSM6100, and amplifying part that amplifies signals coming out from MIC and transferring them
to the audio processor.
2.2.3 MSM6100 (Mobile Station Modem) Part
MSM is the core elements of CDMA terminal and carries out the functions of CPU, encoder,
interleaver, deinterleaver, Viterbi decoder, Mod/Demod, and vocoder.
Z3X-BOX.COM