A new technique for high frequency characterization of capacitors

Abstract

To improve the accuracy for high frequency characterization of capacitors with very low inductance values, a technique is developed. The first part of the technique requires a standard calibration for a network analyzer. Then s-parameter measurements for test fixtures and adapters are measured. A high frequency circuit model for every connector or test fixture from the calibrated port to the device under test (DUT) is then de-embedded one at a time, using the measured data as a reference and each time adding in the previously de-embedded circuit model. The difference between the measured data and the simulated data is forced to be less than 1%. This stringent requirement is necessary for obtaining the high accuracy equivalent series inductance (ESL) and resistance (ESR). The requirement also guarantees the accuracy of high frequency parasitic capacitance and resistance of a capacitor. After the high frequency circuit models for all test fixtures and adapters are found, s-parameter measurements for a capacitor mounted on a test fixture with an adapter are measured. When the circuit models for the test fixture and adapter are put together and the whole system is matched to the measured s-parameter data for the whole system, the circuit model of a capacitor has been found. In this paper, two new capacitor models and several discontinuity models are also reported. The new capacitor models are valid for the entire frequency range. The discontinuity models are fully consistent with the real physical structure of test fixtures. Different capacitors from various suppliers are characterized and the high frequency circuit models are also provided.