Analytical characteristic impedance determination method for microstrip lines fabricated on printed circuit boards

Abstract

An analytical method for determining the characteristic impedance of microstrip lines fabricated on printed circuit board technology is presented. The method is based on a rigorous analysis of the equations involved with the coplanar-waveguide to microstrip transitions composing an actual radio-frequency test fixture, and allows the simultaneous determination of the characteristic impedance and the dominant pad parasitics. The extracted data agree well with the values expected from time domain data, verifying the validity of the method.

Identifying and Modeling Resonance-Related Fluctuations on the Experimental Characteristic Impedance for PCB and On-Chip Transmission Lines

“…Notice that applying (2) to (3) no longer yields Zc, but curves that include fluctuations or glitches introduced by the effect of C and L. These glitches are observed in the Re(Zc) curves in the form shown in Figure 1b when either the inductive or capacitive effects are dominant. In fact, the periodicity and magnitude of these glitches is dependent on the length of the TL as illustrated in Figure 1c [9]. Observe, however, that the fluctuations occur around the expected value for Zc, which suggests that they can be easily removed.…”

“…To contextualize the reader, in this paper several popular methods to obtain Z c are applied to illustrate the effect of the transitions on the experimentally obtained curves. In this regard, in the traditional method, single line measurements are used, but resonances of large magnitude affect the extraction [3,9], even after removing inductive and capacitive parasitics associated with the line terminations [10]. Alternatively, a de-embedding procedure involving measurements performed on two lines varying in length can be applied [11].…”