V1.0 Page 34 of 46 ICM MP CCQ ST
C45, M50 AND MT50 Company Confidential © Copyright Siemens AG 05/02
A/D conversion of MIC-Path signals incl. coding
The Microphone signals (MICN2, MIpN2, MICP1, MICN1) arrive at
the voiceband part of the EGAIM. For further operations the signals will
be converted into digital information, filtered, coded and finally formed
into the GMSK-Signal by the internal GMSK-Modulator.
This so generated signals (MOD_A, MOD_AX, MOD_B, MOD_BX) are
given to the SMARI IC / Bright IC in the transmitter path.
D/A conversion of EP-Path signals incl. decoding
Arriving at the Baseband-Part the demodulated signals (MOD_A, MOD_AX,
MOD_B, MOD_BX ) will be filtered and A/D converted. In the voiceband part
after decoding (with help of the uC part) and filtering the signals will be D/A
converted amplified and given as (EPP1, EPN1, EPP2, EPN2) to the internal
earpiece or the external loudspeaker.
Generation of the PA Control Signal (PA_RAMP)
The RF output power amplifier needs an analog ramp up/down control voltage.
For this the system interface on EGOLD+ generates 10 bit digital values which
have to be transferred serially to the power ramping path. After loading into an
10 bit latch the control value will be converted into the corresponding analog
voltage with a maximum of ~2V
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