A Study On The Modeling Techniques Of Millimeter-wave Coplanar Waveguide

As the developing of the semiconductor technology, the cut-off frequency and maximum operating frequency of transistors increases in a continuous process. According to the reports of International Technology Roadmap for Semiconductors(ITRS), the cut-off frequency of CMOS transistors will increase to 0.9 THz in 2021. Millimeter wave(mm-wave) integrated circuits design is gradually concerned by the industry and academia.As one of the fundamental passive devices in microwave circuit design, Coplanar waveguide(CPW) has many merits, such as low loss, wide range of variation in characteristic impedance, and so on. It is used as interconnect wire in millimeter wave integrated circuits, as well as capacitor or inductor. For the reasons mentioned above, an accurate CPW model would improve the performance of millimeter wave integrated circuits.Nowadays, there are 2 key problems on the study of CPW, one is the inaccuracy of electromagnetic(EM) simulation, and the other is the error between de-embedding data and data of on-wafer measure. Because of these two reasons, the equivalent circuit model of CPW applied to mm-wave integrated circuits is focused to study to fulfill the design requirements in mm-wave integrated circuits design.The inaccuracy of EM simulation, the error in de-embedding and the models of CPW are discussed in depth in this paper, and the specific contents are summarized as follows:1. Based on GaAs and CMOS technology, the CPW structure and its’ characteristics are studied deeply in this paper. Two issues are studied firstly, one is the relations between metal layers and substrate, and the other is the variations of conductivity constant and dielectric constant that result from frequency and process changes. And then, the related parameters of CPW are optimized to make the reasonable agreements between the simulation data and measure data in range from 0.1GHz to 220 GHz. All of these analysis establish the incoming study of de-embedding algorithm and equivalent model, and offer computer aided design for circuits design at the same time.2. A new de-embedding method based on EM simulation was proposed in this thesis, which could help to decrease the cost of tape-out in reason of requiring no de-embedding structure. The proposed method in this paper is better than open and open-short de-embedding methods. And this method achieves the same advantages compared with Thru and Mangan de-embedding methods. Further, the proposed method are more flexible than Thru and Mangan de-embedding methods for that’s does not need extra de-embedding structure.3. Based on GaAs and SMIC 65 nm process, the equivalent circuits of CPW are modeled respectively in this paper. And also a new and convenient method of parameter extraction is proposed in this paper which is based on empirical formulas and measure data. And also, the equivalent model and extraction method are useful for that are verified by using measure results, which are used at frequency from 0.1GHz to 67 GHz.