VCC filtering

A technique for reducing the amount of Radio Frequency Interference spread via power supply connections. VCC is a common name for the non-ground power supply line in circuits based on bipolar transistors.

When part of a circuit generates lots of radio-frequency noise, that portion of the power plane can be isolated from the rest of the circuit and power delivered to it via a low pass filter, usually a PI filter, as shown in the diagram below.

      source   ________inductor_________   load
		  |                |
	      capacitor        capacitor
		  |                |
	       ground           ground

This helps to shield the rest of the circuit from the noise generated by the load.