Goodwin Oscillator
Biological negative feedback generating limit cycle oscillations
The Goodwin oscillator models gene regulatory circuits with negative feedback delay: mRNA (X) → protein (Y) → repressor (Z) → inhibits X. Sustained oscillations require Hill coefficient n ≥ 8 (Griffith criterion) in the basic 3-variable form, modeling circadian clocks, cell cycles, and NF-κB dynamics.