Function sky130_nonideal 

pub fn sky130_nonideal() -> NonIdealityModel

The SKY130-class model.

SOURCE (each figure, per benchmarks/silicon/analog/sourced-constants.md):

• weight_gain_sigma = 0.01 — Hasler, “Large-Scale Field-Programmable Analog Arrays”, Proc. IEEE 108(8) 2020: programmed analog parameters at “better than 1% accuracy” over six decades; we take the 1% envelope as the 1σ class (conservative round-up).
• offset_sigma_v = 2.8e-3 — DERIVED from the SkyWater PDK’s own Monte-Carlo mismatch model (sky130_fd_pr__nfet_01v8__vth0_slope = 3.356e-03 V·µm, pfet 5.856e-03) applied to a stated 5T-OTA example (10µ/0.5µ pair, gm ratio 0.5): σ(V_os) ≈ 2.8 mV. A model-derived example, NOT a published silicon figure (none exists for sky130 — the dossier says so).
• noise_floor_v = 64.4e-6 — kT/C at C = 1 pF, T = 300 K: √(4.142e-21/1e-12) = 64.4 µV rms (Johnson–Nyquist, textbook formula, arithmetic in the dossier).
• gm_distance_sigma_per_pitch = 0.002 — MODELED design parameter (0.2%/pitch): the Pelgrom distance term exists (Pelgrom et al., JSSC 1989) but no sky130 distance coefficient is published; this figure parameterizes the placement machinery until the characterization ladder replaces it, and is labeled MODELED, never silicon.