Audiorfi block

The function of the AUDIO_RFI block is to interface between the digital world of the System Hardware and the analogue world of the audio and RF stages.

Main components include:

- Hands free audio amplifier (N201)

- FET (V200) for amplifier shut down control

- V202 for mic lines' EMI filtering/ESD protection

Technical Documentation 3. RF+System Module KL8

COBBA_GJP is a combined AUDIO- and RF-codec for phones with serial RF TxlQ & RxlQ data lines and serial control interface.

COBBA_GJP handles the following RFI functions:

- IF receiving with I/Q separation and A/D conversion (RxI, RxQ)

- transmit power control (TXC) D/A conversion

- Automatic frequency control (AFC) D/A conversion

Digital communication between COBBA_GJP and MADLinda is handled by MADLinda's SerialMFI block which controls both serial RF TxIQ and RxIQ data transfer and COBBA's control interface.


RAE-5* includes both normal phone audio and personal handsfree (PHF) audio functionality. Handsfree mode is implemented by speaker and normal mode by earpiece. Speaker and earpiece are not located on the KL8 module. Signals for speaker and earpiece are passed through the UI connector. Only one high sensitivity microphone will be used for both modes. On the KL8 module there are contacts pads (P200, P201) where microphone is connected with spring contacts.

Analogue to digital conversion (ADC) of RAE-5's microphone signals and digital to analogue conversion (DAC) of received audio signals (for speakers) are done in COBBA_GJP. Input and output signal source selection and gain control is performed inside the COBBA_GJP according to control messages from MADLinda. Audio tones are generated and encoded by MADLinda and transmitted to COBBA_GJP for decoding. PCM coded digital audio data is moved between MADLinda's DSP and COBBA_GJP through the PCM bus. The audio functions in COBBA_GJP are controlled through the serial control interface from MADLinda's SerialMFI block. DTMF and keypad tones are routed to earpiece, while ringer, wav and handsfree audios are routed to handsfree speaker.

External audio signals, XMIC and XEAR, come from system connector. XMIC is connected to COBBA_GJP's MIC1N and MIC3N inputs through DC blocking capacitors. Reference for XMIC is SGND. XEAR is connected to COB-BA_GJP's HF output through DC blocking capacitors. Reference for XEAR is GND.

Audio amplifier IC (N201) is used to amplify the HF output signal of COB-BA_GJP for the personal hands free speaker. Audio amplifier shut down mode is controlled with MADLinda's MPUGenOut0 line. Because HF amplifier is powered from battery voltage, controlling of shut down is done through pull-down fet (V200).

HeadDet and HookDet interrupting inputs in MADLinda are used to detect different audio accessories. EAD A/D input in CCONT is used to detect the removal of accessory during call.

3. RF+System Module KL8 Technical Documentation

Figure 10 describes the audio connections in system HW.


Audio accessories System connector

I Headset

I Carkit


HookDet HeadDet


SerMFI (control of COBBA)
















UI connector n

Audio Amp.


Figure 10. Audio connections in KL8

Technical Documentation 3. RF+System Module KL8

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