Patent ID: 8907743

Claim:
A delay line structure disposed on a substrate, the substrate including a grounding layer and a layout layer, the grounding layer including a grounding circuit, the delay line structure comprising: a flat spiral delay line disposed in the layout layer extending from an input end, bending clockwise inward until reaching a U-turn part disposed substantially at a central portion of the delay line structure, continuously extending and bending counterclockwise outward to an output end so as to form two coupling areas, which are spiral and have an opening respectively; and two grounding guard traces disposed in the layout layer extending from the openings respectively toward the two coupling areas, each grounding guard trace ending without an interconnective via proximate the central portion of the delay line structure and having an interval between each of the two grounding guard traces and the flat spiral delay line respectively, wherein the two grounding guard traces close to the openings of the two coupling areas are electrically connected to the grounding circuit through a via respectively.