Nokia 12 GSM Module Hardware Integration ... - KORE Telematics

The analog TX path (from the external application to the Nokia 12 module) hasa DC isolation inside the Nokia 12 module with 100 nF capacitors, and thesecapacitors together with the microphone preamplifier input impedance form a 1 storder high pass filter with 32 Hz roll-off (-3 dB).Table 14. Microphone audio characteristicsName Symbol Min Type Max UnitsDifferential inputvoltage range formicrophone input(MICP & MICN)Microphone amplifierinput resistorCommon mode voltagelevel0.316 2.0 V PPRMIC 30 50 kohmVCM 1.3 1.35 1.4 VThe earphone lines from the Nokia 12 module are driven differentially toachieve the best possible audio quality, free of radio frequency noise. In thedifferential mode, positive output is driven from EARP and negative signal fromEARN output.Table 15. Earphone audio characteristicsName Test condition Min Type Max UnitsOutput voltage swingin fully differentialmodeEARP to EARN 0.316 2 V PPOutput resistance 1 ohmLoad resistanceLoad resistanceLoad capacitanceCommon voltage levelfor Earphone outputEARP to EARN(with dynamictransducer)EARP to EARN(with externalaudio circuitry)EARP to EARN(with externalaudio circuitry)30 45 ohm1 kohm10 nFVCMEar 0.75 0.8 0.85 VOffset voltage -50 50 mV20/44