Synthesis of Power Distribution to Manage Signal Integrity in Mixed-Signal ICs - Tapa dura

In the early days of VLSI, the design of the power distribution for an integrated cir­ cuit was rather simple. Power distribution --the design of the geometric topology for the network of wires that connect the various power supplies, the widths of the indi­ vidual segments for each of these wires, the number and location of the power I/O pins around the periphery of the chip --was simple because the chips were simpler. Few available wiring layers forced floorplans that allowed simple, planar (non-over­ lapping) power networks. Lower speeds and circuit density made the choice of the wire widths easier: we made them just fat enough to avoid resistive voltage drops due to switching currents in the supply network. And we just didn't need enormous num­ bers of power and ground pins on the package for the chips to work. It's not so simple any more. Increased integration has forced us to focus on reliability concerns such as metal elec­ tromigration, which affects wire sizing decisions in the power network. Extra metal layers have allowed more flexibility in the topological layout of the power networks.

The move to higher levels of integration has increased the fraction of application-specific integrated circuit (ASIC) designs containing both analog and digital circuits. While the die area for the analog portion of these chips is modest, the design time is often significant. This has motivated the development of automated analog physical design tools for cell-level place-and-route and system-level signal-integrity-routing. To date, there is no tool that has specifically addressed the critical design task of synthesizing the power distribution for the analog portion of an analog or mixed-signal ASIC. Synthesis of Power Distribution to Manage Signal Integrity in Mixed-Signal ICs describes algorithms for analog power distribution synthesis and demonstrates their effectiveness. Existing digital power bus synthesis algorithms have failed to address critical concerns for analog circuitry, thus yielding unacceptable results. These tools synthesize only the bus component of power distribution networks and only consider simplified DC aspects of macros and busses. Readers of the companion book in this series, Simulation Techniques and Solutions for Mixed-Signal Coupling in Integrated Circuits (Kluwer Academic Publishers), already recognize the inadequacy of this simplified view of the noise and power distribution problem in mixed-signal integrated circuits. Synthesis of Power Distribution to Manage Signal Integrity in Mixed-Signal ICs addresses power distribution synthesis for mixed-signal integrated circuits. Several key challenges in power distribution design are identified and automated methods to overcome them are described. This book presents a new formulation for the analog power distribution synthesis problem which synthesizes both the power busses power I/O cell assignment by evaluating DC, AC, and transient interaction between the macros, busses, chip substrate, and package. Furthermore, algorithms are introduced which simultaneously optimize power I/O cell assignment, macro cell substrate coupling, power bus topology selection and power bus sizing. Synthesis of Power Distribution to Manage Signal Integrity in Mixed-Signal ICs will be of interest to CAD designers and researchers specializing in physical design, modelling and circuit synthesis.