Analog and radio frequency system-level simulation using frequency relaxation. Embodiments of the invention use a frequency relaxation approach for analog/RF system-level simulation that accommodates both large system size and complex signal space. The simulator can determine an output response for a system by partitioning the system into blocks and simulating the propagation of an input signal through the blocks. The input signal can take various forms, including a multi-tone sinusoidal signal, a continuous spectra signal, and/or a stochastic signal. Frequency relaxation is applied to produce individual responses. The output response can be computed based on obtaining convergence of the individual responses. The input to embodiments of the simulator can be a circuit netlist, or a block-level macromodel.