RapidMoM

Full-wave Method of Moments for planar layouts in layered media.

RapidMoM is a full-wave solver for the passive structure of RF circuits: the metal of a chip or a board in its layered stack, read from GDS. It computes the network of that structure at its ports, S, Y and Z from DC up, and the current and charge on every conductor that the network comes from.

A complete block

A 180 GHz four-way power amplifier from IHP's open SG13G2 tape-outs, taken as drawn. Every metal level is meshed and every transistor terminal and pad is a port: 56 ports, 230,945 unknowns. One frequency is one exact solve, 27 minutes on 16 threads. Charge and current are that solve with the input driven, on log scales: the signal path stands out of the ground.

Devices

The conductor model is chosen per metal: one sheet for thin wiring and grids, both faces, or faces and side walls where skin and proximity effects decide the loss. The far field comes from the same layered Green's function as the solve, so substrate and ground shape the pattern.

Under the hood

A mixed-potential integral equation in augmented form, accurate down to DC. The Green's functions of a stack are tabulated once and reused across devices and frequencies. The system is compressed into an H-matrix and solved by block GMRES for all ports at once, preconditioned by a sparse LU of the near field from RSLAB ; a solve grows as N log N. Written in Rust, used from Python, a command line or a project file.

History

The first prototypes of a 2D Method of Moments date from March 2026; development proper started in June 2026, in the same push that produced RapidMesh and RSLAB : the planar solver, its mesher and its linear algebra grew together as one vertically integrated unit.