User's Manual

XT55/56 Hardware Interface Description
Confidential / Released
s
XT55/56_hd_v02.06a Page 106 of 125 17.12.2004
6.5.5 Voiceband transmit path
Test conditions:
• The values specified below were tested to 1kHz and 0dB gain stage, unless otherwise
stated.
• Parameter setup: Audio mode = 5 for GSM_MICP1 to GSM_MICN1 and 6 for
GSM_MICP2 to GSM_MICN2, inBbcGain= 0, inCalibrate = 32767, outBbcGain = 0,
OutCalibrate = 16384, sideTone = 0
Table 33: Voiceband transmit path
Parameter Min Typ Max Unit Test condition/Remark
Input voltage (peak to peak)
GSM_MICP1 to GSM_MICN1,
GSM_MICP2 to GSM_MICN2
1.03 V
Input amplifier gain in 6dB steps
(inBbcGain)
0 42 dB Set with AT^SNFI
Fine scaling by DSP (inCalibrate) - 0 dB Set with AT^SNFI
Input impedance GSM_MIC1 50 k
Input impedance GSM_MIC2 2.0 k
Microphone supply voltage ON
Ri = 4k (GSM_MIC2 only)
2.57
2.17
1.77
2.65
2.25
1.85
2.73
2.33
1.93
V
V
V
no supply current
@ 100µA
@ 200µA
Microphone supply voltage OFF;
Ri = 4k (GSM_MIC2 only)
0 V
Microphone supply in POWER
DOWN mode
See Figure 16