Our customer, a major semiconductor company, was developing a mixed signal IC for an international wireless handset company. The product specification required several DC-DC converters that operated over wide load ranges. The customer wanted to investigate control systems that could optimize battery life, noise, and transient load regulation. The controller was required to automatically detect and select a power optimized control mode. Simulation time using physical circuit components would consumed massive amounts of computing resources and designer time. IC Design Services provided a VerilogA based hybrid model( part physical components, part code) that included different control techniques(PFM, Hysteretic, fixed frequency) in transient mode simulation and switched under simulation control. Simulation time was reduced to less that one hour per simulator evaluation cycle. After the final circuit design was completed, the physical design was compared to the Verilog-A model with nearly identical results.