Nine-Element Lumped Metal Finger Capacitor Model Extraction Method for RF Applications

The need for a good capacitor model increases as the operating frequency approaches the Gigahertz range. A good capacitor model should fairly characterize the behavior of the capacitor to include other passive characteristics such as the resistance and inductance, not to forget the parasitic elements. Presented here is a method to extract lumped element models for metal finger capacitors. The model suggested is a nine element pi circuit that includes interconnect resistance and inductance as well as substrate parasitics. This paper identifies the procedures to extract the nine element lumped metal finger capacitor model and to optimize the model to fit the measured data up to the self resonant frequency. A good fit between the modeled and measured effective capacitance and Q factor have been obtained in this work . This method can also be applied to MIM capacitors.