I. Introduction
Modern millimeter-wave imaging systems [1] need ultra fast tunable, compact and cost effective signal sources. The use of high operational frequencies and fast frequency tuning is resulting in higher image resolution and improved system performance. The realization of high frequency sources by a phase locked voltage controlled oscillator (VCO) becomes more difficult with increasing frequency. A combination of both, a multiplier chain and a low frequency source can solve this problem. Frequency multiplier chains convert fast tunable and high quality low frequency signals into the millimeterwave frequency range.