Multimedia ICs
•Measurement circuit
10kΩ
8
5kΩ
10µF
9
MIX BF
+
–
BA7760 / BA7760F
2.2kΩ
+
7
4.7µF
5kΩ
6
470µF
+
+
47µF
10
11
220Ω
+
12
4.7µF
2.2kΩ
13
–+
+–
14
BA7760 / F
5
4
220Ω
4.7µF
+
3
2.2kΩ
2
470µF
+
+
47µF
+
1
22µF
Fig. 2
•Circuit operation (Refer to “Application Example”)
The BA7760 and BA7760F are dual microphone ampli-
fiers. The audio signals from the microphones are input
to pins 3 and 12. The gain at this time is determined by
attached resistors R3 / R4 and R6 / R7. By attaching
capacitors to pins 5 and 10, the microphone amplifiers
can be given frequency characteristics like those
shown below.
(Note: The attached component numbers are those used in “Application
Example.”)
60dB
40dB
20dB
C
=
C
150pF
=
0
0dB
180°
– 20dB
0°
3
1kHz
61 3 61 3
10kHz 100kHz
16M1 Hz31601MHz310601M–H1z80°
FREQUENCY : f (Hz)
Characteristics when using standard
components and standard constants
Fig. 3 Microphone amplifier
frequency characteristics
4