SGM721_16 Datasheet, PDF (11/21 Pages) SG Micro Corp – CMOS Operational Amplifiers

SGM721/2/3/4
TYPICAL APPLICATION CIRCUITS
Differential Amplifier
The circuit shown in Figure 4 performs the difference
function. If the resistor ratios are equal (R₄/R₃ = R₂/R₁),
then V_OUT = (V_P - V_n) × R₂/R₁ + V_REF.
R2
R1
Vn
VP
R3
SGM721
R4
VOUT
VREF
Figure 4. Differential Amplifier
Instrumentation Amplifier
The circuit in Figure 5 performs the same function as
that in Figure 4 but with a high input impedance.
11MHz, Rail-to-Rail I/O
CMOS Operational Amplifiers
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 bandwidth 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 resistor values as low as
possible and consistent with output loading
consideration.
R1
VIN
C
R2
SGM721
VOUT
R3=R1//R2
SGM721
Vn
Vp
SGM721
R2
R1
SGM721
R3
R4
VOUT
VREF
Figure 5. Instrumentation Amplifier
Figure 6. Low-Pass Active Filter
SG Micro Corp
11
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