The Research Of Terahertz Frequency Tripler Based On Schottky Diodes

Acted as local oscillator in the transceiver or radiator in the receiver, frequencymultiplier is one of key elements of terahertz systems. As the technology of terahertzdeveloped rapidly, more stringent requirements of the frequency multipliers arepresented, such as higher output frequency, higher efficiency, greater output power andlarger bandwidth. Therefore, it is necessary and important to research high-performanceterahertz frequency multipliers. The master thesis mainly focus on the design of triplerat some practical frequencies, including the design of190GHz frequency tripler basedon RAL varactor diode and103.5GHz frequency tripler employing MA46H146varactordiode, as well as wide band frequency tripler using DBES105A varistor diode. Themain works of the thesis are summarized as follows:1. Load-pull technology which extracts the embedding impedances of diode isemployed to design high efficiency frequency multipliers. A190GHz frequency tripleris developed based on the aforementioned methods. In the measurement, for a fixedinput drive power of70mW, the maximum efficiency is more than4.6%at the177GHz,and3.27mW output power is achieved with-2.6V DC bias. In the174-184GHzfrequency range, the output power is greater than2mW. The measured results are notagreement with the simulated because of lacking of accurate SPICE parameters and3Dconfiguration of diode chip.2. The SPICE model is discussed. Some crucial SPICE model parameters ofMA46H146varactor diode is extracted, such as Cj0, using parameter extraction theory.Then a high-efficiency, high-power103.5GHz tripler is designed based on theaforementioned results. For a fixed input drive power of140mW, the measured outputpower is greater than7mW, and efficiency is about5%with-5.3V DC bias for eachSchottky varactor diodes, as well as10mW output power or more is achieved in the99GHz,102GHz,106GHz, respectively. When the DC bias is changed as-6.2V, in the102GHz, the maximum14.4mW output power and10%efficiency are obtained with140mW input drive power. To our knowledge, the maximum output power andefficiency of the tripler is first reported at this frequency in our country. 3. For a fixed IF (intermediate frequency) receiver system, the performance ofwide band of local oscillator is requirement. Therefore, a wide band103.5GHz tripler isdeveloped employing DBES105A Schottky varistor diodes. There is no DC bias in theconfiguration, so the structure of tripler is simplified greatly, and it is also convenient tomeasure. For a fixed140mW input drive power, the measured output power is greaterthan7mW in the103.5GHz, and efficiency is more than5%. In the77-127GHzfrequency range, the output power is greater than2mW. The performance of the triplerwe designed can compete with the products developed by VDI. Now, the wide bandtripler we designed has replaced the relative products designed by VDI in the220GHzterahertz imaging system.