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Conclusion

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Conclusion

The chopper op amp, due to its internal switching architecture, generates current spikes on

its input pins. This explains why the average input bias current of a chopper is slightly higher

than a traditional op amp.

Depending on the application environment, these input current spikes, of a few µA, might

make some designers apprehensive about using a chopper op amp.

However, we have seen in this application note that using a chopper with a high impedance

sensor tends to limit the amplitude of these spikes and it should not disturb the sensor.

Moreover, adding a common mode capacitor also helps to filter the input current spikes. The

value of this capacitor must be chosen carefully in order to keep the whole system stable.

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Revision history

Table 2. Document revision history

Date

Revision

Changes

28-Oct-2014

1

Initial release