This paper proposes a tool for the synthesis of the design and optimization of digitally controlled pulse width modulator (PWM). There are three phases for the proposed tool. In the first phase, an accurate transistor level model for 90 nm fabrication technology is generated using MATLAB curve-fitting tool box (Dunbar in Am J Phys 24(6):464–464, 1956) and Cadence Spectre Circuit Simulator, which successfully replicates the transistor performance of Cadence 90 nm fabrication technology. In the second phase, the PWM specification is optimally decomposed among its subcomponents. The optimized design of subcomponents is accomplished via Geometric programming in the third phase. A practical design example in Cadence 90 nm fabrication technology is presented to substantiate the suggested methodology for unified design automation and power optimization.