Analysis of propagation delays in high-speed VLSI circuits using a distributed line model

A scattering parameter-based homogeneous distributed-line model with arbitrary initial and boundary conditions is proposed and its implementation in a general-purpose circuit simulator supporting user functions is described. Using a GaAs 0.5-μm MESFET technology, the chip delays in very high-speed VLSI circuits are calculated. The performance requirements of transistors for high-density integration and for long-distance interconnection drivers are discussed with respect to properties of lossy and lossless interconnection lines. The evaluation of chip delays shows that sub-100-ps VLSI circuits (gate count beyond 10 ⁵) should involve: (1) complementary logic gates using transistors with transconductance of 1-2.5 S/mm; and (2) high T _c superconducting long-distance interconnection lines driven by bipolar circuits with transconductance of 2.5 S/mm, unless such long lines can be overcome by new chip architectures