Present and Future Capability of Millimeter Wave Pumped Paramps

Parametric amplifiers have been extensively used in many varied and sophisticated applications (communications, radar, ECM, etc.), through Ku-band, in which relatively high cutoff frequency packaged varactors, with a self-resonance frequency in the 20- to 30-GHz range, have been utilized. The extension of paramps into higher frequencies (above 20 GHz) had been limited by both the cutoff frequency of the varactor, and the package parasitic reactances and losses that limited the upper useful frequency. Over the past few years, significant improvements in varactor technology have been made that have yielded much higher cutoff frequencies [approximately 600 GHz at zero (0) volt bias], coupled with low parasities, that result in a self-resonant frequency in the 60-GHz region. A diagram of this field proven varactor is shown in Figure 1. This improved varactor has made extremely low-noise temperature paramps available in the microwave region and has also resulted in the achievement of broader instantaneous bandwidths than had been previously obtained. Recently, further improvements in varactor technology have led to higher cutoff frequencies [above 1000 GHz @ zero (0) vikt bias] that will further enhance not only the achievable noise temperature and bandwidth capability of paramps in the microwave region, but will also enable the development of completely solid-state paramps in the millimeter wave region. These newly developed varactors have already been successfully used, up to 300 GHz, as frequency multipliers. The recent developments and expected performance, utilizing these advanced varactors, willbe presented.