A unifying and robust method for efficient envelope-following simulation of PWM/PFM DC-DC converters

The envelope-following (EF) simulation of practical DC-DC converters is challenging due to the presence of digital behavior, strong nonlinearity, complex frequency module schemes and feedback loops. This paper presents a novel EF method for time-domain analysis of DC-DC converters based upon a numerically robust time-delayed phase condition to track the envelopes oaf circuit states under a varying switching frequency. We further develop an EF technique that is applicable to both fixed and varying switching frequency operations, thereby providing a unifying solution to converters with pulse-width modulation (PWM) and/or pulse-frequency modulation (PFM). The robustness and efficiency of the proposed method are demonstrated using several DC-DC converter and oscillator circuits modeled using the industrial standard BSIM4 transistor models. A significant runtime speedup of 30× with respect to the conventional transient analysis is achieved for PFM DC-DC converters with strong nonlinear switching characteristics.