By Nadia Kari | 01/08/2017
Microstrip to Coplanar waveguide transitionIn hybrid integrated circuits design, transition between microstrip and CPW is essential. This article demonstrates the application of HFWorks and SolidWorks to design and simulate a transition from microstrip line to coplanar waveguide. This approach of using HFWorks and SolidWorks is ideal for such applications because the structure can be easily modeled and simulated inside SolidWorks. One of the methods to realize microstrip to CPW transition is based on two couples of microstrip-to-slot line transitions.A broadband transition from microstrip to CPW is presented in this article.The structure fundamentally utilizes two pairs of microstrip-to-slotline transitions to achieve this.At the lower frequency below the passband, the input impedance contains capacitive reactance. To counteract the capacitive reactance, a short-ended microstrip stub is introduced to connect in parallel with the microstrip line. The S Parameters simulation in HFWorks was used to simulate the transition from microstrip to CPW for hybrid integrated circuits. Figure 1 shows the 3D model of the transition from microstrip line to CPW.
Figure 1 - 3D model of the transition from microstrip line to CPW (a) top view of the model, (b) bottom view of the modelThe layout of the transition from Microstrip to CPW is depicted in figure 2, the gemeometrical results are summarized in table 1.
Figure 2 - Layout of the microstrip-to-CPW transition structure with a shortended microstrip stub
Simulation ResultsFigure 3 shows a comparison between the simulated results of S parameters and the appropriate measurements of a single microstrip-to-CPW transition. The two results are in goodagreement. The simulated results indicate that, for the return loss ofbetter than 10 dB, a broad bandwidth of 2.05 to 9.96 GHz is achieved.
Figure 3 - Return and insertion loss of the transition from microstrip to CPW (dB)The maximum and minimum insertion losses of thetransition passband are 1.7 dB and 0.2 dB, respectively.