msm6722gs-k Oki Semiconductor, msm6722gs-k Datasheet - Page 10

• Manufacturer Part Number: msm6722gs-k
• Description: Pitch Control Ic For The Speech Signal
• Manufacturer: Oki Semiconductor

¡ Semiconductor
Analog Input Amplifier Circuit
The MSM6722 has two built-in operational amplifiers for amplifying the microphone output.
Each output amplifier is provided with an inverting input pin and output pin. The analog circuit
reference voltage SG (signal ground) is connected internally to the non-inverting input of each
output amplifier. For amplification, form an inverting amplifier circuit and adjust the amplifi-
cation ratio by using external resistors, as shown below.
The output V
allowable input voltage (V
must be adjusted so that the V
For example, if V
voltage range, the output of the LPF will be a clipped waveform. The load resistance R
the OP amplifier is 200 kW or more. Therefore, the feedback resistors R2 and R4 of the inverting
amplifier circuit must be 200 kW or more.
SG
–
V
IN
LO
+
of output amplifier 2 is connected to the input FIN of the built-in LPF. The FIN
R1
MIN
DD
V
LO
=
= 5 V, V
R4
R3
–
+
R2
FIN
OP amplifier 1
V
LO
LO
) ranges from 1 V to (V
MO
MOUT
amplitude can be within the FIN allowable input voltage range.
V
becomes 3 V
=
MO
R2 • R4
R1 • R3
R3
LIN
V
IN
p-p
R4
–
+
(V)
max. If V
OP amplifier 2
DD
LOUT
V
–1) V. Therefore, the amplification ratio
LO
LO

   


V
exceeds the FIN allowable input
LO
MSM6722
V
V
1/2 V
1
GND
DD
DD
OUTA
–1
10/18
DD
of