TC9470FN

2002-02-27

7

The digitalization of the de-emphasis filter eliminates the need for such external components as resistors,

condensers and analog switches. In addition to this, the coefficients are aligned to reduce error in the

de-emphasis filter characteristics.

The filter structure and characteristics are shown below.

5. Dynamic Digital Bass Boost Circuit

ON/OFF for the dynamic digital bass boost is controlled in the parallel mode ( S

P/

= “H”) with the DBB1

pin (pin 20) and the DBB2 pin (pin 21).

This is set in the serial mode ( S

P/

= “L”) with a microcontroller or other equipment. (refer to 10.2

microcontroller setting mode for further details on serial mode settings.)

A block diagram for the dynamic bass boost circuit is shown in Figure 6.

The compressor’s compression ratio when in the control mode for the parallel mode is shown below.

Table 3 Compressor Compression Ratio (when in the parallel mode)

DBB max

18dB

DBB MID

12dB

The compressor’s compression characteristics are as follows:

Table 4 Compressor Compression Characteristics (when in the parallel mode)

DBB max

−36dB

DBB MID

−24dB

Figure 6 Dynamic Digital Bass Boost Circuit Block

+

INPUT

OUTPUT

SERIAL

ATTENUATOR

COMPRESSOR BLOCK

L.P.F

Coefficient length: 7 bits

Figure 4 IIR Digital De-Emphasis Filter

Figure 5 Filter Characteristics

1

/T

1

2

/T

1

+

+

Input data

Z

−1

)

-

+

=

-

-

1

1

1

1

0

Z

a

(1

)

Z

b

(b

(Z)

H

:

function

Transfer