AN6077 INTERSIL [Intersil Corporation], AN6077 Datasheet - Page 9

• Manufacturer Part Number: AN6077
• Description: An IC Operational Transconductance Amplifier With Power Capability
• Manufacturer: INTERSIL [Intersil Corporation]

Note that the expressions for high frequency gain are
identical for both bass circuits, while the expressions for low
frequency gain are identical for the treble circuits.
Figure B2 shows cut and boost bass and treble controls that
have the characteristics of the circuits of Figure B1. The
value R
the parallel combination of R
control is rotated to its maximum counterclockwise position.
When the control is rotated to its maximum clockwise
position, the value is equal to R
To compute the circuit constants, it is necessary to decide in
advance the amounts of boost and cut desired. The gain
expressions of Figure B1 indicate that the slope of the
amplitude versus frequency curve in each case will be 6dB
per octave (20dB per decade). If the ratios of boosted and
cut gain are set at 10, i.e.
A
A
=
=
A
R
---------------------------------- -
LOW FREQUENCY
EFF
C
-------------------- -
1
FIGURE B1. FOUR OPERATIONAL AMPLIFIER CIRCUIT CONFIGURATIONS AND THE GAIN EXPRESSIONS FOR EACH
1
+
C
+
A
R
R
4
in the treble controls of Figure B1 is derived from
C
LOW FREQUENCY
2
2
4
+
FIGURE B1 (C). TREBLE BOOST
FIGURE B1 (A). BASS BOOST
R
1
--------------------------------------------------------------------------------------------- -
3
+
C
1
SR
1
--------------------------------------------------------------- -
R
+
E
2
EFF
S
SC
E
=
S
1
1
1
---------------------------------------------------------------
R
---------------------------------- -
C
+
4-9
----------------------------------------- -
+
1
C
1
R
R
1
SR
SR
3
+
-
and R
+
2
C
1
=
R
1
R
-
+
R
R
4
+
.
R
EFF
3
EFF
3
C
-------------------- -
2
2
+
3
R
C
C
+
1
+
C
C
C
2
1
1
+
2
1
R
C
R
C
3
+
4
+
4
C
of Figure B2 when the
1
C
3
3
R
C
R
R
4
4
1
3
3
4
+
E
C
O
E
1
O
C
3
Application Note 6077
:
Bass Circuit: A
Treble Circuit: A
then the following relationships result:
Bass Circuit: R
Treble Circuit: C
A
A
=
=
A
R
---------------------------------- -
LOW FREQUENCY
C
-------------------- -
1
R
1
+
C
2
+
R
A
A
R
+
4
C
2
LOW FREQUENCY
C
LOW Boost
LOW Cut
1
3
C
R
A
+
4
1
HIGH Boost
1
2
3
=
=
HIGH Cut
R
FIGURE B1 (D). TREBLE CUT
=
=
1
--------------------------------------------------------------------------------------------- -
3
FIGURE B1 (B). BASS CUT
99R
10R
R
+
10C
10C
------------- -
C
C
2
99
1
--------------------------------------------------------------- -
SR
2
2
R
2
2
R
+
3
EFF
4
1
4
=
EFF
SC
E
1
E
+
=
S
+
=
A
------------- -
S
=
SC2
MID
10
2
SR
R
---------------------------------- -
=
10A
---------------------------------------------------------------
----------------------------------------- -
A
------------- -
C
1
R
R
10A
R
10
MID
1
+
EFF
2
1
2
C
+
=
MID
-
R
-------------------- -
R
R
+
-
+
R
+
4
R
3
MID
2
2
C
-------------------- -
1
R
+
R
2
+
C
C
+
+
1
R
2
C
3
C
C
R
1
1
R
R
+
3
4
+
2
4
1
+
+
3
3
C
C
R
R
C
C
4
4
3
3
4
2
+
E
C
O
1
E
C
O
2