US Patent 7375983 Circuit board for reducing crosstalk of signals

A circuit board includes a first group of layers located close to a top side of the circuit board, and a second group of layers located close to an underside of the circuit board. Signals which are fed to input and output contact terminals on the top side of the circuit board are passed along at least one of the layers of the group. Signals which are fed to input and output contact terminals on the underside of the circuit board are passed along at least one of the layers of the second group. The contact-making holes for connecting the input and output contact terminals to the layers of the first and second groups are preferably formed as blind contact-making holes.