The ferroelectric capacitor model is the foundation for accurate simulation of ferroelectric hysteresis loops and minor loops, transitions between the loops under arbitrary voltage patterns, transient responses of ferroelectric capacitors to short voltage pulses with widths in the nano-second range, and temperature behaviors of ferroelectric capacitors. The simulation speed is the same as that for a typical nonlinear capacitor. To the circuit designers, a ferroelectric capacitor is represented as a two-port device like a capacitor. The parameters are extracted easily and reliably by curve fitting the measured hysteresis loops. The model is applicable to fast circuit simulations for large ferroelectric memory designs.