A closed-loop multistage ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$n$</tex> </formula> -stage) multiphase ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$p$</tex> </formula> -phase) switched-capacitor boost dc–ac inverter (MPSCI) is proposed by combining a variable-phase control (VPC) and sinusoidal pulsewidth-modulation (SPWM) technique for low-power step-up inversion/regulation. Its power stage contains two parts: an MPSC booster (front) and an H-bridge (rear). An <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$n$</tex></formula> -stage <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$p$</tex></formula> -phase MPSC is for an inductor-less boost dc–dc conversion, where <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$n$</tex></formula> voltage doublers are in series for boosting voltage gain up to <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$2^{n}$</tex> </formula> at most. For improving efficiency, VPC is suggested to realize a variable multiphase operation by changing phase number <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$p$</tex></formula> and topological path for more suitable gain level. An H-bridge is employed for dc–ac conversion, where four switches are controlled by SPWM not only for full-wave operation, but also for enhancing output regulation as well as robustness to source/loading variation. The analysis and design include an MPSCI model, steady-state/dynamic analysis, conversion ratio, power efficiency, stability, capacitance selection, total harmonic distortion (THD), filter, and control design. Finally, the closed-loop MPSCI is simulated, and the hardware is implemented and tested. All results are illustrated to show the efficacy of the proposed scheme.