CXA1550P, CXA1551M/P, CXA1552M/P, CXA1553M/P
5) MPX filter termination and C
1
for V
CC
/2 (Pin 4)
The MPX (multiplex) filter termination method shown in Fig. 1 allows saving the coupling capacitors
between the buffer amplifiers and MPX filters. However, the channel to channel separation and REC to PB
crosstalk of low frequency signals will be degraded by the termination resistor RT. For example, 5 kΩ of R
1
will degrade the channel to channel separation to 50 dB. Better separation can be obtained by increasing
the capacitance of C
1
(Pin 4) to 220 µF or 470 µF.
The allowable minimum value of C
1
is 47 µF, and 100 µF is the standard recommended value. Larger
values of C
1
are generally desirable in order to improve the crosstalk and ripple rejection ratio.
6) Application for dubbing cassette decks
The CXA1550 series generates non decoded signal at the recoding output in the playback (decode) mode,
and can simplify the structure of dubbing decks. See the Sony’ Dolby B/C type IC (CX20187/CXA1097Q or
CX20188/CXA1098Q) data sheet in detail.
Line
Input
Buffer
MPX
Filter
C11
4.7µ
R
T
16
15
14
13
CXA1550 Series
R
T
Line
Input
Buffer
MPX
Filter
1
2
3
4
C21
4.7µ
C1
470µ
Fig. 1
—10—
SONY [ SONY CORPORATION ]
