Hybrid inductor modeling for successful filter design

A method for deriving accurate L-band inductor models using I-port fixtured S-parameter measurements is presented, along with examples of successful filter designs using the models. Models were developed for a number of surface-mount and leaded devices with values ranging from 4.7 nH to 470 nH. The devices were measured in a coaxial test fixture on an HP8510B network analyzer, with fixture de-embedding performed using CAD software. The models are seen to fit measured data over a broadband, from low RF through resonance. To further validate the models, several filter circuits were developed and fabricated. The results of 5th- and 9th-order lowpass filter designs are presented here. The 9th-order filter was optimized for the desired performance using the parasitic inductor models. Measurements confirm that the use of the models led to a successful design on the “first pass.” Finally, simulations show that this success would not have been achieved without the developed inductor models