| In this thesis, a constant and grounded capacitor model for MOS transistor is proposed for circuit simulation and timing simulation. The model, based on the well known one by Hodges and Jackson, accounts for most of the physical and processing parameters that influence the transient times. This model takes the advantage of the fully complementary MOS technology which is widely used in today's industry for VLSI circuits.;In the model, all the energy storage effects of a MOSFET are first represented by equivalent constant terminal capacitances including constant floating ones. Furthermore, each of these floating capacitances is replaced by two constant grounded ones, replacing the two terminals of the original floating one. The model with floating capacitors is much more accurate but is better suited for circuit simulation than for timing simulation. The largest error in the model with constant grounded capacitances results from the feed-forward effect. The methods to overcome this effect, and the conditions under which it is significant, are discussed. The experiments show that this new constant grounded capacitance model can get much more accurate results than the one by Hodges and Jackson. Agreement with the HSPICE circuit simulator is within 10% in most of the cases. |
