LMC6484 Datasheet, PDF (28/45 Pages) National Semiconductor (TI) – CMOS Quad Rail-to-Rail Input and Output Operational Amplifier

LMC6484
SNOS675C – AUGUST 2000 – REVISED SEPTEMBER 2015
Typical Application (continued)
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Figure 53. Canceling the Effect of Input Capacitance
The effect of input capacitance can be compensated for by adding a feedback capacitor. The feedback capacitor
(as in Figure 53), Cf, is first estimated by Equation 1:
1
1
³
2pR₁ C_IN 2pR₂ C_f
or
R₁ C_IN £ R₂ C_f
(1)
which typically provides significant overcompensation. Printed circuit board stray capacitance may be larger or
smaller than that of a breadboard, so the actual optimum value for C_f may be different. The values of Cf should
be checked on the actual circuit. (Refer to the LMC660 Quad CMOS Amplifier data sheet (SNOSBZ3) for a more
detailed discussion.)
8.2.2.3 Offset Voltage Adjustment
Offset voltage adjustment circuits are illustrated in Figure 54 and Figure 55. Large value resistances and
potentiometers are used to reduce power consumption while providing typically ±2.5 mV of adjustment range,
referred to the input, for both configurations with V_S = ±5 V.
Figure 54. Inverting Configuration
Offset Voltage Adjustment
Figure 55. Noninverting Configuration
Offset Voltage Adjustment
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