| 摘要 |
A circuit board has a first signal layer having a set of conductors, a second signal layer having a conductive plane and a non-conductive region, and a third signal layer having a conductive region that mirrors the non-conductive region of the second signal layer. The circuit board further includes a first separating layer having non-conductive material which is disposed between the first signal layer and the second signal layer, and a second separating layer having non-conductive material which is disposed between the second signal layer and the third signal layer. Accordingly, traces within the first signal layer and overlying the conductive plane of the second signal layer will have a first impedance, while traces within the first signal layer and overlying the non-conductive region of the second signal layer and the conductive region of the third signal layer will have a second impedance that is different than the first impedance.
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