Impedance Estimation of Internal Nodes of RF Devices based on Measurement Cable De-Embedding Enabled by Transmission Line Model Fitting

Abstract

Fixtures and adapters introduce parasitic effects in radiofrequency (RF) components measurements, which unwantedly transform their impedances. To remove the effects of coaxial measurement cables, this paper presents a de-embedding method based on transmission line (TL) model fitting in 400-3000 MHz range. The method uses numerically fitted TL parameters: characteristic impedance and electrical length to extract the terminal impedance of any device under test (DUT). We have used two different DUTs with the 8 cm long flexible coaxial connector to extract these parameters. As proof of concept, an experimental validation of a quarter-wave transformer confirms that the de-embedded impedance correlates closely with simulations across the broad frequency range considered.