SGM721 Datasheet, PDF (10/18 Pages) SG Micro Corp – 970μA, 10MHz, Rail-to-Rail I/O CMOS Operational Amplifier

Typical Application Circuits
Differential Amplifier
The circuit shown in Figure 4 performs the difference function.
If the resistors ratios are equal ( R4 / R3 = R2 / R1 ), then
VOUT = ( Vp – Vn ) × R2 / R1 + Vref.
R2
R1
Vn
Vp
R3
SGM721
R4
Vref
V_OUT
Figure 4. Differential Amplifier
Instrumentation Amplifier
The circuit in Figure 5 performs the same function as that in
Figure 4 but with the high input impedance.
SGM721
Vn
Vp
SGM721
R2
R1
SGM721
R3
R4
V_OUT
Vref
R1
V_IN
C
R2
SGM721
V_OUT
R3=R1//R2
Figure 6. Low Pass Active Filter
Figure 5. Instrumentation Amplifier
Low Pass Active Filter
The low pass filter shown in Figure 6 has a DC gain of (-R₂/R₁)
and the –3dB corner frequency is 1/2πR₂C. Make sure the filter
is within the bandwidth of the amplifier. The Large values of
feedback resistors can couple with parasitic capacitance and
cause undesired effects such as ringing or oscillation in
high-speed amplifiers. Keep resistors value as low as possible
and consistent with output loading consideration.
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