LMC6044

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SNOS612D – NOVEMBER 1994 – REVISED MARCH 2013

Figure 28. LMC6044 Noninverting Gain of 10 Amplifier, Compensated to Handle Capacitive Loads

In the circuit of Figure 28, R1 and C1 serve to counteract the loss of phase margin by feeding the high frequency

component of the output signal back to the amplifier's inverting input, thereby preserving phase margin in the

overall feedback loop.

resistor conducting 10

μA or more will significantly improve capacitive load responses. The value of the pull up

resistor must be determined based on the current sinking capability of the amplifier with respect to the desired

output swing. Open loop gain of the amplifier can also be affected by the pull up resistor (see Electrical

Characteristics).

Figure 29. Compensating for Large Capacitive Loads with a Pull Up Resistor

PRINTED-CIRCUIT-BOARD LAYOUT FOR HIGH-IMPEDANCE WORK

It is generally recognized that any circuit which must operate with less than 1000 pA of leakage current requires

special layout of the PC board. When one wishes to take advantage of the ultra-low bias current of the

LMC6044, typically less than 2 fA, it is essential to have an excellent layout. Fortunately, the techniques of

obtaining low leakages are quite simple. First, the user must not ignore the surface leakage of the PC board,

even though it may sometimes appear acceptably low, because under conditions of high humidity or dust or

contamination, the surface leakage will be appreciable.

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