lpc660imx National Semiconductor Corporation, lpc660imx Datasheet - Page 10

• Manufacturer Part Number: lpc660imx
• Description: Low Power Cmos Quad Operational Amplifier
• Manufacturer: National Semiconductor Corporation

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normally considered a very large resistance, could leak 5 pA
if the trace were a 5V bus adjacent to the pad of an input.
This would cause a 100 times degradation from the
LPC660’s actual performance. However, if a guard ring is
held within 5 mV of the inputs, then even a resistance of
FIGURE 4. Example of Guard Ring in P.C. Board Layout using the LPC660
(Continued)
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perhaps a minor (2:1) degradation of the amplifier’s perfor-
mance. See Figure 5a, Figure 5b, Figure 5c for typical
connections of guard rings for standard op-amp configura-
tions. If both inputs are active and at high impedance, the
guard can be tied to ground and still provide some protec-
tion; see Figure 5d.
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ohms would cause only 0.05 pA of leakage current, or
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