Tackling close-to-band passivity violations in passive macro-modeling

Passivity enforcement is important for macro-modeling for passive systems from measured or simulated S-parameter data. State-space systems generated from vector fitting usually present strong passivity violation outside the frequency bandwidth especially in the close-to-band (CTB) region. Removing such close-to-band violation is very difficult with existing passivity enforcement techniques without severely sacrificing the accuracy of the model. In this paper we propose a frequency data extension method which aims to reduce or even eliminate such close-to-band violations without sacrificing model accuracy. The generated model can be used in a later stage for further passivity enforcement. Experiments show that with applying the proposed method, the accuracy of the generated model can be significantly improved.