Copyright

© ANPEC Electronics Corp.

Rev. A.4 - Jan., 2013

www.anpec.com.tw

18

APA3160

Function Description (Cont.)

Dynamic Range Control (DRC)

The DRC scheme has a single threshold, offset, and slope (all programmable). There is one ganged DRC for the left/

right channels.

The DRC input/output diagram is shown in Figure 15.

Professional-quality dynamic range compression automatically ad-

justs volume to flatten volume level.

• One DRC for left/right.

• The DRC has adjustable threshold, offset, and compression levels.

• Programmable energy, attack, and decay time constants.

• Transparent compression: compressors can attack fast enough to

avoid apparent clipping before engaging, and decay times can be set

slow enough to avoid pumping.

Figure 15. Dynamic Range Control

T

Input Level (dB)

K

O

1:1 Transfer Function

Implemented Transfer Function

Energy Filter

Compression

Control

Attack and

Decay Filters

α, ω

T, K, O

α

0x3B/0x3C

0x40,0x41,0x42

0x3A

DRC

Audio Input

DRC

Coefficient

Σ

α

ω

Alpha Filter Structure

Note :

ω=1-α

Figure 16. DRC Structure

Biquad Structure

All biquads use a 2nd order IIR filter structure as shown below. Each biquad has 3 coefficients on the direct path (b0,

b1, b2) and 2 coefficients on feedback path (a1 and a2) which is shown in the diagram.

Σ

Magnitude

Trunction

x(n)

y(n)

b

0

b

1

b

2

a

1

a

2

Figure 17. Biquad Filter