ha17902fpk Renesas Electronics Corporation., ha17902fpk Datasheet - Page 12

• Manufacturer Part Number: ha17902fpk
• Description: Quad Operational Amplifier
• Manufacturer: Renesas Electronics Corporation.

HA17902 Series
3. High Input Impedance DC Differential Amplifier
4. Voltage Controlled Oscillator
12
The circuit shown in figure 3 is a high input impedance DC differential amplifier. This circuit’s
common-mode rejection ratio (CMR) depends on the matching between the R
ratios. This amplifier’s output is given by the following formula.
Figure 4 shows an oscillator circuit in which the amplifier A
comparator, and transistor Q
Vout1 is at the low level, this will cut off transistor Q1 and cause the A
potential than the noninverting input. Therefore, A
level will decrease. When the A
input level (V
integrate a positive input state and for its output to increase. This operation generates a square wave on
Vout1 and a triangular wave on Vout2.
Vout = 1 +
CC
/2) the comparator output goes high. This turns on transistor Q
Figure 3 High Input Impedance DC Differential Amplifier
R
R
4
3
(V
V
V
+V
1
2
2
C
Figure 4 Voltage Controlled Oscillator
– V
1
operates as a switch that controls the oscillator frequency. If the output
100k
1
1
100k
R
R
)
integrator output becomes lower than the A
1
Q
1
R/2
50k
51k
–
+
100k
R
2
51k
C 0.05 F
–
HA17902
+
V
A
100k
CC
1
10k
R
1
3
V
will integrate this negative input state and its output
CC
/2
100k
+
–
+
–
HA17902
100k
R
V
4
A
CC
2
1
is an integrator, the amplifier A
Vout1
Vout2
Vout
1
inverting input to go to a higher
2
1
comparator noninverting
1
/R
causing the integrator to
2
and R
4
/R
3
resistance
2
is a