KA9270
AUDIO FILTER
APPLICATION INFORMATION
1. BUFFER
INPUT
+
(from D/A Converter
-
Output)
to De-emphasis input
Fig. 3
It is used for impedance matching, between D/A converter output and de-emphasis input.
2. DE-EMPHASIS
a) De-emphasis operation condition
Control Input
High
Low
De-emphasis Operation
ON
OFF
b) De-emphasis characteristic at the de-emphasis ON
R5
C1
R4
R6
Vi
-
Vo
+
Fig. 4 Equevalent Circuit of De-emphasis ON Mode
Av R4 / R6
T1 = C1 (R4 + R5)
T2 = C1 X R5
The de-emphasis charcteristics is dependent on the external parts value.