Abstract: To improve the simulation accuracy of SIMULINK,a novel inclusive behavior model of an integrator is proposed that introduces the effects of different circuit nonidealities of a switched-capacitor sigma-delta modulator into SIMULIK simulation.The nonlinear DC gain and nonlinear settling process are introduced into the op-amp module.The signal-dependent charge injection and nonlinear resistance are introduced into the switch module.In addition,the noise source including flicker and thermal noise is introduced into system as an independent module.The novel model is verified by SIMULINK behavioral simulations.The results are compared with results from circuit level simulation in Cadence SPICE using TSMC 0.35μm mixed signal technology.It shows that the novel model succeeds in introducing the influences of the nonidealities into behavior simulation to more realistically describe the circuit performances and increase the accuracy of SIMULINK simulation.

Key words: sigma-delta modulator, nonlinear DC gain, feed-through, slewing distortion, phase margin, charge injection