8KX-TG8421E/KX-TG8422E/KX-TG8423E/KX-TG8424E/KX-TGA840E4.2. Circuit Operation (Base Unit)4.2.1. OutlineBase 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
