insertion & return loss. As frequency increases attenuation losses are also increases which contribute inaccuracy in the measurement of S parameter [1]. Earlier there are different methods discovered for characterization of DUT. In order to meet these high speed requirements the design engineer must consider and minimize all the factors that impact the integrity of the digital signals in order to ensure the correct system functioning [7]. Adapting a coaxial test cable to a Microstrip device requires an adequate test fixture and a suitable de-embedding technique for removing the effects of the test fixture from the device under test (DUT). This further evaluates the de-embedding problem and the phase errors introduced when using test fixtures [7]. At RF improved accuracy & reduced attenuation losses achieved by fixture free measurement of DUT & well calibrates probes using SOLT calibration performed on wafer ISS (Short, open, load, thru).
II. Methods used FOR DUT characterization
A. Port Extension Method It is used to remove the effects of the test fixture. It shifts the reference plane till the ends of the fixture but it is less accurate in practical environments. As the number of the fixtures increases inaccuracy in measurement is also increased. Advancement of port extension is the adopter removal method.