High Speed

Among analog-to-digital converters, the delta-sigma modulator has cornered the market on high to very high resolution converters at moderate speeds, with typical applications such as digital audio and instrumentation. Interest has recently increased in delta-sigma circuits built with a continuous-time loop filter rather than the more common switched-capacitor approach.

The appropriate interconnect model has changed several times over the past two decades due to the application of aggressive technology scaling. New, more accurate interconnect models are required to manage the changing physical characteristics of integrated circuits. Currently, RC models are used to analyze high resistance nets while capacitive models are used for less resistive interconnect. However, on-chip inductance is becoming more important with integrated circuits operating at higher frequencies, since the inductive impedance is proportional to the frequency. The operating frequencies of integrated circuits have increased dramatically over the past decade and are expected to maintain the same rate of increase over the next decade, approaching 10 GHz by the year 2012. Also, wide wires are frequently encountered in important global nets, such as clock distribution networks and in upper metal layers, and performance requirements are pushing the introduction of new materials for low resistance interconnect, such as copper interconnect already used in many commercial CMOS technologies.