Datasheet

–3
–2.5
–2
–1.5
–1
–0.5
0
0.5
1
1.5
2
0 1000 2000 3000 4000 5000 6000 7000
Rx_8K_1st_HPF
Rx_8K_3rd_HPF
Specification
Frequency(Hz)
VoiceDownlink(RX)Filter16kHz
032-031
Gain(dB)
TPS65950
SWCS032E–OCTOBER 2008–REVISED JANUARY 2011 www.ti.com
6.1.9.2 Voice Downlink Filter (Sampling Frequency at 16 kHz)
Figure 6-18 shows the voice downlink frequency response with F
S
= 16 kHz. Table 6-13 lists the voice
filter frequency responses relative to the reference gain at 1 kHz with F
S
= 16 kHz.
Figure 6-18. Voice Downlink Frequency Response With F
S
= 16 kHz
Table 6-13. Digital Voice Filter RX Electrical Characteristics With F
S
= 16 kHz
Parameter Test Conditions Min Typ Max Unit
Frequency response relative to reference gain at 1 kHz (first-order 300 to 6600 Hz –0.5 0 0.5 dB
HPF)
6800 Hz –1.5 0 0.1
8000 Hz –17
9200 Hz –40
> 12000 Hz –45
Pole when third-order HPF is disabled (first-order HPF) 5 Hz
6.1.10 Boost Stage
The boost effect adds emphasis to low frequencies. It compensates for an HPF created by the
capacitance resistor (CR) filter of the headset (in ac-coupling configuration).
There are four modes. Three effects are available, with slightly different frequency responses, and the
fourth setting disables the boost effect:
• Boost effect 1
• Boost effect 2
• Boost effect 3
• Flat equalization: The boost effect is in bypass mode.
Table 6-14 and Table 6-15 list typical values according to frequency response versus input frequency and
F
S
frequency.
82 Audio/Voice Module Copyright © 2008–2011, Texas Instruments Incorporated
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