A multistage power CMOS-transmission-gate-based (CMOS-TG) quasi-switched-capacitor (QSC) boost DC-AC inverter is proposed and integrated with a boost DC-DC converter for a step-up application with AC or DC load. In this paper, using CMOS-TG as a bidirectional switch, the various topologies can be integrated in the same configuration for achieving two functions: boosting and alternating; boosting for getting a sinusoidal output in which the peak is the result of a many times step-up of the input; alternating to realize the positive/negative half sinusoidal of the output. The inverter does not require any inductive elements as inductor and transformer, so integrated circuit (IC) fabrication will be promising for realization. By using the state-space averaging technique, the large-signal state-space model of the inverter is proposed, and then both the static analysis and dynamic small-signal analysis are derived to form a unified formulation for inverter/converter. Based on this formulation, there are presented for theoretical analysis/control design, including steady-state power, conversion efficiency, voltage conversion ratio, output ripple percentage, capacitance selection, closed-loop control and stability, and total harmonic distortion (THD), etc. Finally, a six-stage QSC boost DC-AC inverter is simulated by PSPICE, and the simulations are discussed for some cases, including: 1) steady-state AC output, ripple percentage, and power efficiency; 2) transient response of the regulated inverter for load variation; 3) a practical capacitive load: electromagnetic luminescent (EL) lamp, and 4) efficiency, ripple percentage, and THD for different loads. The results are illustrated to show the efficacy of the proposed inverter.