Techniques for routing and shielding signal lines to improve isolation between the signal lines are disclosed. In an exemplary design, an apparatus includes first, second, and third signal lines and a switch. The first, second, and third signal lines are configurable to carry first, second, and third signals, respectively. The switch is coupled between the second signal line and AC ground and is closed when the second signal line is not carrying the second signal. The second signal line isolates the first and third signal lines when the switch is closed. Adjacent signal lines are not active at the same time. A signal line may include positive and negative signal lines, which may have at least one cross over in order to cancel coupling between the positive and negative signal lines.