TCM4400E Datasheet, PDF (51/64 Pages) Texas Instruments – GSM/DCS BASEBAND AND VOICE A/D AND D/A RF INTERFACE CIRCUIT

TCM4400E
GSM/DCS BASEBAND AND VOICE A/D
AND D/A RF INTERFACE CIRCUIT
SLWS082A – JULY 1999 – REVISED MARCH 2000
PRINCIPLES OF OPERATION
voiceband uplink control register
The values in the voiceband uplink control register bit positions control not only the power level of the audio in
the uplink path but also set the gain of the PGA from –12 dB to 12 dB in 1 dB steps. Bit MICBIAS and VULMIC
and VULAUX are shifted by one position to the left. This is shown in Table 17.
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _VDXMUTE
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ _R/W
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ₀
MICBIAS
R /W
0
Table 17. Voiceband Uplink Control Register
VBCTL1: VOICEBAND UPLINK CONTROL REGISTER
VULMIC VULAUX VULPG4 VULPG3 VULPG2 VULPG1
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
VULPG0
R/W
0
VULON
R/W
0
ADDRESS: 10 R/W
0 1 0 1 0 1/0
<–ACCESS TYPE
<–VALUE AT RESET
VULON:
Power on the uplink path of the audio codec
VULAUX:
Enables the auxiliary input amplifier if bit VULON is 1
VULMICL:
Enables the microphone input amplifier if bit VULON is 1
MICBIAS:
When MICBIAS = 0, the analog bias for the electret-type microphone and external
decoupling is driven to 2 V; when the value is 1, the bias is 2.5 V.
VDXMUTE:
When VDXMUTE = 1, the VDX output is forced to zero, when the value is 0, VDX is
transmitted normally. To avoid cutting a VDX word during transmission due to
asynchronism of writing this bit via DSP or MCU serial interface, VDXMUTE is internally
resynchronized with the 8 KHz voice frame.
VULPG (0–4):
Gain of the voice uplink programmable gain amplifier (–12 dB to 12 dB in 1 dB step), see
Table 18.
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