A 270-GHz Tuner-Less Heterostructure Barrier Varactor Frequency Tripler

A tuner-less heterostructure barrier varactor (HBV) frequency tripler has been designed, fabricated, and tested. A conversion efficiency of 7.2% and output power of 6.5 mW were measured at 270 GHz with 90 mW of input power. The performance of this tuner-less HBV tripler is comparable with other HBV frequency multipliers reported in the literature that utilize mechanical tuners to optimize their performance     

High-order subharmonically pumped mixers using phased local oscillators

A high-order subharmonically pumped mixer architecture that utilizes multiple pairs of antiparallel diodes is described. A key component of the mixer architecture is a K-way power-divider/phase shifter that divides the local oscillator (LO) to multiple ports with equal magnitude and prescribed phase shifts. Undesired mixing products are eliminated through phase cancellation by symmetry rather than relying on intermediate idler circuits. As a proof-of-principle demonstration, an eighth-order mixer is implemented based on this approach and has shown a measured conversion loss of 8 dB at 8 GHz. The mixer architecture is suitable for applications in the millimeter and submillimeter-wave regions where high-frequency LOs are difficult to implement.     

Analysis of an octagonal micromachined horn antenna forsubmillimeter-wave applications

An analysis is presented of a new horn antenna, fabricated by a novel micromachining technique, that uses crystallographic etching of silicon and ultraviolet lithography of an ultra-thick photoresist (SU-8). The horn was found to have low cross-polarized field levels and a predicted Gaussian coupling efficiency of 92.5%. The horn shape is governed by the crystal planes of the silicon substrate and the thickness of the photoresist and has up to four independent design parameters that allow a wide range of antenna patterns. A design for the horn that yields symmetric beam patterns was investigated by computer analysis, microwave scale modeling, and measurements of a micromachined horn at 585 GHz. The major features of the 585-GHz beam patterns agree well with the computer-generated and scaled beam patterns. We have thus demonstrated a new micromachinable horn that has great potential for integration into array structures     

A 100-element planar Schottky diode grid mixer

The authors present a Schottky diode grid mixer suitable for mixing or detecting quasi-optical signals. The mixer is a planar bow-tie grid structure periodically loaded with diodes. A simple transmission line model is used to predict the reflection coefficient of the grid to a normally incident plane wave. The grid mixer power handling and dynamic range scales as the number of devices in the grid. A 10-GHz 100-element grid mixer has shown an improvement in dynamic range of 16.3 to 19.8 dB over an equivalent single-diode mixer. The conversion loss and noise figure of the grid are equal to those of a conventional mixer. The quasi-optical coupling of the input signals makes the grid mixer suitable for millimeter-wave and submillimeter-wave applications by eliminating waveguide sidewall losses and machining difficulties. The planar property of the grid potentially allows thousands of devices to be integrated monolithically     

Terahertz detector utilizing two-dimensional electronic fluid

We report on the first implementation of a terahertz detector utilizing two-dimensional (2-D) electronic fluid in a high electron mobility transistor (HEMT) operating at 2.5 THz. The terahertz radiation induced a dc drain-to-source voltage proportional to the radiation intensity. The measured dependencies of the detector responsivity on the gate bias are in good agreement with the gate bias dependence of the normalized responsivity predicted by the detector theory. This result shows the potential for developing a new family of electronics devices-plasma wave electronics devices-operating at terahertz frequencies