STA381BWS_V01 datasheet(32/174 Pages) STMICROELECTRONICS

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Device overview

STA381BWS

32/174

DocID018937 Rev 7

4.3.1

STC block diagram

Figure 10. STCompressorTM block diagram

The STC takes as input 2 channels and every channel is processed independently (i.e. an

independent DRC for each band of each channel) following the steps listed below

(Figure 10):

Splits the input signal into 2 bands (band splitter)

Measures the level of the signal (level meter)

Computes the attenuation (mapper)

Applies the attenuation and offset (attenuator)

The band splitter settings are common to both the processing channels while the settings of

the remaining blocks can be independently set for each band of each processing channel.

Caution:

All the settings explained hereafter apply only to the behavior of the STCompressorTM. For

the settings concerning other device operating configurations (see Chapter 4.1: Processing

data path) please refer to the appropriate paragraphs and registers.

4.3.2

Band splitter

The band splitter block is used to divide the signal into 2 sub-bands (typically low- and high-

frequency bands). This is done through two 2nd order biquads (IIR filters) for each band,

thus allowing to have up to a 4th order filter per band. This feature guarantees a totally flat

band recombination (see Figure 11). Using different filtering orders, indeed, causes a non-

negligible gain around the filter’s cutoff frequency, endangering the overall audio fidelity and,

eventually, also the safety of the speaker. The sub-band recombination can be enabled or

disabled.

Level

Meter

Map p er

Attenuator

Offs et

Level

Meter

Map p er

Attenuator

Offs et

Ban d

Sp litter

Ban d 0

(Lo w freq s)

Ban d 1

(Hig h freq s)

In p ut

Ch 0

Outp ut

Ch 0

DRC 0

DRC 1

Lev el

Meter

Map p er

Atten uato r

Offset

Lev el

Meter

Map p er

Atten uato r

Offset

Ban d

Sp litter

Ban d 0

(Lo w freq s )

Ban d 1

(Hig h freq s)

In p ut

Ch 1

Outp ut

Ch 1

DRC 2

DRC 3

Obsolete

Product(s)

- Obsolete

Product(s)

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