SGM321 Datasheet, PDF (8/18 Pages) SG Micro Corp – 1MHz, 60μA, Rail-to-Rail I/O CMOS Operational Amplifier

Typical Application Circuits
Differential Amplifier
The circuit shown in Figure 4 performs the difference function. If
R1
the resistors ratios are equal ( R4 / R3 = R2 / R1 ), then
V_IN
VOUT = ( Vp – Vn ) × R2 / R1 + Vref.
R2
C
R2
SGM321
V_OUT
R1
Vn
Vp
R3
SGM321
R4
Vref
V_OUT
R3 = R1 // R2
Figure 6. Low Pass Active Filter
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.
SGM321
Vn
Vp
SGM321
R2
R1
SGM321
R3
R4
V_OUT
Vref
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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SGM321/358/324