20 CIRCUIT OPERATION (BASE UNIT)
20.1. Outline
Base Unit consists of the following ICs as shown in
BLOCK DIAGRAM (BASE UNIT)
(P.58).
•
DECT BBIC (
B
ase
B
and IC): IC8
−
Handling all the audio, signal and data processing needed in a DECT base unit
−
Controlling the DECT specific physical layer and radio section (
B
urst
M
odule
C
ontroller section)
−
ADPCM codec filter for speech encoding and speech decoding (DSP section)
−
Echo-cancellation and Echo-suppression (DSP section)
−
Any tones (tone, sidetone, ringing tone, etc.) generation (DSP section)
−
DTMF receiver (DSP section)
−
Clock Generation for RF Module
−
ADC, DAC, timer, and power control circuitry
−
All interfaces (ex: RF module, EEPROM, RINGER, Analog Front End, etc.)
•
RF Module: IC9
−
PLL Oscillator
−
Detector
−
Compress/Expander
−
First/Second Mixer
−
Amplifier for transmission and reception
•
EEPROM: IC4
−
Temporary operating parameters (for RF, etc.)
Note:
Refer to
EEPROM LAYOUT (BASE UNIT)
(P.71)
•
Serial Flash ROM: IC6
−
4M bit
−
Audio data for TAM operation
•
Additionally,
−
Power Supply Circuit (+4.0V, +2.65V output)
−
Crystal Circuit (10.368MHz)
−
Charge Circuit
−
Telephone Line Interface Circuit
59
KX-TCD445BXS / KX-TCD445BXT / KX-TCD445BXF / KX-A144BXS / KX-A144BXT / KX-A144BXF /