This proposal is responsive to NASA SBIR Subtopic S1.02: Microwave Technologies for Remote Sensing, specifically the interest in frequency multipliers that can work in the 200-400GHz range (output frequency) with better than 30% efficiency and input powers up to 1W. VDI will employ three specific innovations to achieve the power and efficiency goals described in the solicitation. 1) Optimization of the use of diamond heat spreaders to achieve improved thermal management and therefore lower diode operating temperatures. 2) Development of a practical method of four-way, in-phase power combining within the multiplier housing. 3) The use of active biasing technology to ensure that the diodes are automatically at their optimal bias point even as the source frequency is rapidly tuned across the operating band. Additionally a prototype amplifier-multiplier chain will be delivered to NASA JPL, demonstrating the feasibility of these innovations.