LMC6464QML

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SNOSAR8A – DECEMBER 2010 – REVISED MARCH 2013

Figure 38. Pulse Response of LMC6464 Circuit in Figure 37

The pulse response of the circuit shown in Figure 37 is shown in Figure 38.

COMPENSATING FOR INPUT CAPACITANCE

It is quite common to use large values of feedback resistance with amplifiers that have ultra-low input current,

like the LMC6464. Large feedback resistors can react with small values of input capacitance due to transducers,

photodiodes, and circuits board parasitics to reduce phase margins.

Figure 39. Canceling the Effect of Input Capacitance

The effect of input capacitance can be compensated for by adding a feedback capacitor. The feedback capacitor

(1)

or

(2)

which typically provides significant overcompensation.

Printed circuit board stray capacitance may be larger or smaller than that of a breadboard, so the actual optimum

quad CMOS amplifier data sheet for a more detailed discussion.)

OFFSET VOLTAGE ADJUSTMENT

Offset voltage adjustment circuits are illustrated in Figure 40 and Figure 41. Large value resistances and

potentiometers are used to reduce power consumption while providing typically ±2.5 mV of adjustment range,

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