This paper presents the design and development of a 190 GHz Schottky-diode frequency doubler (x2 multiplier) which can handle up to 260 mW input power. In order to increase the power handling capability, a modeling approach incorporating computer-aided design (CAD) load-pull techniques to characterize the diode performance is proposed. By the use of this approach, effects of several critical diode parameters on the power handling issue are quantitatively investigated and based on the analysis, a discrete diode chip is designed for the doubler. To ensure rapid heat sink in the doubler circuitry, low cost aluminum nitride ceramic (AlN) is selected as the dielectric material of the circuit substrate, which has significantly better thermal conductivity compared with currently widely-used fused quartz. The doubler circuitry is based on a balanced configuration, which brings a merit of avoiding the use of a filter for the input and output signal isolation. The doubler circuit is optimized by co-simulation using ANSYS's HFSS and Keysight's ADS. The measurements show that the doubler can handle up to 260 mW input power with a power conversion efficiency of nearly 8%, resulting in 20 mW output power at 193 GHz.