US Patent 8378223 Delay line structure

A delay line structure disposed on a substrate having a dielectric base layer formed with a via, a layout layer and a grounding layer with a grounding circuit, includes two parallel spiral delay lines having a first outer straight section, a first outer bent section, an inner spiral region, a second outer bent section and a second outer straight section. The inner spiral region bends reciprocally between the first and second outer straight sections to form several inner bent parts and several inner straight parts. A grounding guard trace is disposed among the first and second outer straight sections and the inner straight parts and is coupled electrically to the grounding circuit, wherein each of the first and second outer bent sections and the inner bent parts has a width smaller than each of the first and second outer straight sections and the inner straight parts.