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DA802

ANT2

ANT1

RXp

RXn

ANT2

ANT1

TXp

TXn

KX-TG6811/6821 BLOCK DIAGRAM (Base Unit_RF Part)

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(BBIC, Flash Memory, EERROM) is a digital speech/signal processing system that implements all the functions of speechcom-
pression, record and playback, and memory management required in a digital telephone answering machine.The BBIC system
is fully controlled by a host processor. The host processor provides activation and control of all that functionsas follows.

• Voice Message Recording/Play back

The BBIC system uses a proprietary speech compression technique to record and store voice message in Flash Memory.An
error correction algorithm is used to enable playback of these messages from the Flash Memory.

• DTMF Generator

When the DTMF data from the handset is received, the DTMF signal is output.

• Synthesized Voice (Pre-recorded message)

The BBIC implements synthesized Voice, utilizing the built in speech detector and a Flash Memory, which stored the vocabulary.

• Caller ID demodulation

The BBIC implements monitor and demodulate the FSK/DTMF signals that provide CID information from the Central Office.

• Digital Switching

The voice signal from telephone line is transmitted to the handset or the voice signal from the handset is transmitted to theTele-
phone line, etc. They are determined by the signal path route operation of voice signal.

• Block Interface Circuit

RF part, LED, Key scan, Speaker, Telephone line.

Following information data is stored.

• Voice signal

ex: Pre-recorded Greeting message, Incoming message

Following information data is stored.

• Settings

ex: message numbers, ID code, Flash Time, Tone/Pulse

RF part

ADPCM

Analog
Front
End

&
  
Multi-
plexer

TEL
Line
Interface

Digital
Speech
Processor

Caller ID
Modem

Digital TAM  System

*1

Flash Memory  IC601

*1

 Host CPU

DECT RF system
 TDMA/TDD
 Mod/Demod
 PA/LNA

ADPCM

Keys/ LEDs/ Charge

*1

EEPROM IC611

*1 for KX-TG6821 only

Speaker

*1

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• Bell signal detection
• ON/OFF hook and pulse dial circuit
• Side tone circuit

In the idle mode, Q141 is open to cut the DC loop current and decrease the ring load. When ring voltage appears at the Tip (T)
and Ring (R) leads (When the telephone rings), the AC ring voltage is transferred as follows:
R 

 P101  R111  C111  Q111  BBIC pin 5

When the CPU (BBIC) detects a ring signal, Q141 turns on, thus providing an off-hook condition (active DC current flow
throughthe circuit). Following signal flow is the DC current flow.
T 

 D101  Q141  Q161  R163  D101  P101  R

Q141 is open, Q141 is connected as to cut the DC loop current and to cut the voice signal. The unit is consequently in an on-
hook condition.

Pin 6 of BBIC turns Q141 ON/OFF to make the pulse dialing.

Basically this circuit prevents the TX signal from feeding back to RX signal. As for this unit, TX signal feed back from Q161 is
canceled by the canceller circuit of BBIC.

During pulse dialling the hookswitch (Q141, Q142) is used to generate the pulses using the HOOK control signal, which is set
high during pulses. To force the line impedance low during the “pause” intervals between dial pulses, the PULSE_DIAL signal
turns on Q140.

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The power supply voltage from AC adaptor is converted to VBAT (3.0V) in 3.0V Regulator (IC302). And +3.0V for peripherals
and analog part is insulated from VBAT by Doubler of BBIC.
Circuit Operation:

5.5V

VBAT

RSTN(Reset) 

pin 54

VBAT

pin 10

pin 57

pin 9

pin 15

IC501

IC302

IC601

BBIC

DOUBLER OUT
For peripherals

VDDC (1.2V)

AC Adaptor

3.0V

REGULATOR

FLASH

IC611

EEPROM

+3.0V

STM/CKM

Receive

Amp.

MSG LED

Startmonitor

(IC501 57pin)

VDDC (1.2 V)

VBAT

Reset (RSTN) 
(IC501_54 pin)

BBIC chip initialize

(CKM/STM)

RF Part

           LED
(TAM COUNTER)