Voltage regulator mandatory for arduino shield?

Hi all, I'm new to electronics so my question might sound stupid...

If I'm building a capacitive touch shield for arduino, is a voltage regulator required? Please take a look at the application circuit from the IC specifications:

http://www.tontek.com.tw/download.asp?sn=475

The application circuit calls for a voltage regulator. If it's not mandatory and I want to build the shield without one, how should the circuit look like?

Many thanks!

What's wrong with the regulated voltage available from the Arduino?

What's wrong with the regulated voltage available from the Arduino?

Meaning "use the regulated 5V from your Arduino".