Multilayer coplanar waveguide for high speed digital applications

The authors present measurements of pulse distortion, coupling, and loss due to discontinuities of the coplanar waveguide (CPW) on single and multilayer structures. The CPW compares favorably to the microstrip line in terms of low coupling and distortion. A novel metal-backed coplanar waveguide on a multilayer structure is introduced to minimize or eliminate pulse distortion due to overmoding. The new CPW structure also has the advantage of relatively low loss at discontinuities. For a T circuit, the loss per bend in the new structure was about 0.2 dB less than a similar microstrip line.<>