An FPGA-based MOS circuit simulator

A novel method for performing SPICE-like circuit simulations on a field programmable gate array (FPGA) is presented. An RC filter and an NMOS transistor have been simulated as demonstration examples. The presented technique utilizes a digital signal-processing object (SPO) that is analogous to an analog operational amplifier. An array of SPOs solves nonlinear difference equations in the same way that an array of opamps solves nonlinear differential equations. The SPO is first designed in Simulink and then emulated in the Xilinx system generator. This model is then programmed onto an FPGA, Spartan-3, e.g. The simulation result is virtually identical to a standard SPICE simulation, but simulation speed is increased by more than an order of magnitude, as compared to simulations running on typical workstations. This is because a typical FPGA holds many SPOs, all running in parallel at a high clock rate. Advantages are: 1) speed of execution with little or no degradation in the accuracy, 2) no parallel programming step since the SPO interconnections are specified by the difference equations and 3) the resulting FPGA can act as a high speed attached processor to the workstation.