On Die Decoupling Capacitor?

On-chip decoupling capacitors are widely used in today's high-performance microprocessor design to mitigate the power supply noise problem. The continued reduction of oxide thickness in advanced nanotechnology, however, also significantly increases the tunneling current and leakage power of thin-oxide capacitors.

What is the purpose of using a decoupling capacitor?

In the case of input voltage drop, a decoupling capacitor provides adequate power to an IC to maintain the voltage level. In the case of voltage increase, a decoupling capacitor prevents the excess current from flowing through the IC to keep the voltage stable.

Where do you place a decoupling capacitor?

Decoupling capacitors should be placed as close as possible to the source for the signal being decoupled. This means at the pin for ICs and near the connector for input and out signals. To remove LF transients from input and output signals, the capacitor should be placed in series with the trace.