This paper proposes the overlapped block relaxation Newton method for greatly reducing the number of iterations needed for simulating large scale nonlinear circuits. The circuit is partitioned into subcircuits, i.e., overlapped blocks consisting of core nodes and overlapped nodes. The core nodes form the core circuit for each overlapped block and the overlapped nodes form the overlapped circuit. The Newton-Raphson method is applied to all overlapped blocks independently and the approximation vector for relaxation is determined by node voltages of core nodes. An overlapped circuit is considered to be the representative circuit of the outside circuit for the core circuit. Therefore, the accuracy of the approximation vector for relaxation may be improved and the number of relaxation steps may be greatly reduced. Core nodes are determined automatically by reflecting the circuit structure, then the overlapping level is determined automatically. We show that this method has good performance for simulating large scale circuits, and that it is faster than the nonlinear direct method which is used in standard circuit simulators.

This paper describes an innovative, high-speed optical backboard bus composed of an optical star coupler, optical-transmitter modules, optical-receiver modules, and optical multi-mode glass fibers. A highly efficient optical coupling structure with an aspherical lens and a laser diode was designed to achieve a coupling efficiency of 90%, enabling distribution of optical signals at up to 1 Gb/s to 50 function boards. Embedded optical fibers in a printed circuit board were used to achieve precise control of the optical propagation delay times and permit a high packaging density. We developed small laser-diode and photo-diode modules suitable for optical coupling with the embedded fibers. A fabricated prototype optical backboard bus controlled by a controller IC mounted on a function board was able to successfully distribute high-speed optical signals to function boards with a high packaging density.