KX-TG2521RUT, KX-TGA251RUT — Panasonic Telephone Service Manual (repair manual). Page 8

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8
KX-TG2521RUT/KX-TGA251RUT
4.2.
Circuit Operation (Base Unit)
4.2.1.
Outline
Base Unit consists of the following ICs as shown in Block Diagram (Base Unit) (P.7).
• DECT BBIC (Base Band IC): IC7
- Handling all the audio, signal and data processing needed in a DECT base unit
- Controlling the DECT specific physical layer and radio section (Burst Module Controller section)
- ADPCM code 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
- PLL Oscillator
- Detector 
- Compress/Expander
- First Mixer
- All interfaces (ex: RF Power Amp, EEPROM, LED, Analog Front End, etc.)
• RF Power Amp.: IC801
- Amplifier for transmission and reception
• EEPROM: IC401
- Temporary operating parameters (for RF, etc.)
• FLASH MEMORY: IC421
- Voice Prompt (TAM) D/L Area
- ICM/OGM Recording Area
• Additionally,
- Power Supply Circuit (+3.0 V, +2.4 V, +1.8 V output)
- Crystal Circuit (10.368 MHz)
- Charge Circuit
- Telephone Line Interface Circuit

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