On determining the characteristic impedance of low-loss transmission lines

Abstract

Characteristic-impedance (Z 0

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

“…Moreover, these simplified models allow the straightforward determination of the involved parameters. On the contrary, the equations that consider both parameters simultaneously introduce more complexity to the analysis, which may be unnecessary since the dominant pad parasitics associated with microstrip lines embedded between CPW adapters are typically either shunt capacitive or series inductive [8]. For our case of study, this is verified in Figure 5 where the time-impedance profile obtained from TDR (time domain reflectometry) data corresponding to a microstrip line of 25 mm is shown.…”

“…(6) explicitly identifies the real and imaginary parts of Z sqU , which is crucial to analytically extract the characteristic impedance from experimental data rather than using optimization methods such as the one reported in [8]. The only assumption made in the derivation of eq.…”

“…However, when the effect of the parasitic inductance L d is important, this assumption is not valid and a careful analysis of the ABCD matrix has to be performed for the determination of Z c . To carry out this analysis, the squared uncorrected impedance can be defined as [8]:…”

“…Another way to represent the transitions occurring in an actual RF test-fixture is by using the concept of error boxes [7,8]. Thus, when these boxes are mathematically removed from the measurements, the resulting data can be directly associated with the DUT.…”

“…Thus, when these boxes are mathematically removed from the measurements, the resulting data can be directly associated with the DUT. Unfortunately, the complexity of the mathematics involved in the modeling of the CPW-to-microstrip (CPW-M) transitions complicates the analytical determination of the error parameters, leading to the development of parameter-optimization approaches [8].…”