Time-domain noise analysis of linear time-invariant and linear time-variant systems using MATLAB and HSPICE

A custom simulation tool that combines HSPICE and MATLAB to enable time-domain noise analysis is reported. The simulation technique is based on computing the statistics of a random process by ensemble averaging and is applicable to both linear time-invariant (LTI) and linear time-variant (LTV) systems. MATLAB is used to generate a set of representative noise signals, which are imported into HSPICE for simulation. Once the simulations are complete the results are read back into MATLAB and ensemble statistics are calculated. The MATLAB-generated noise signals have a user-defined white-noise floor and flicker noise corner frequency and thus are suitable for modeling a wide variety of electronic components, including CMOS transistors and resistors. Simulation results of the time-dependent output noise of a gated integrator and the timing resolution of a gated integrator/comparator detector are presented to highlight both the utility and the versatility of the tool.