Critical Temperature Dependence of High Frequency Electron Dynamics in Superconducting Hot-Electron Bolometer Mixers Irfan Siddiqi May, 2002 Superconducting diffusion-cooled hot-electron bolometer (HEB) mixers are ideal candidates for use in terahertz heterodyne spectroscopy (THz). This thesis investigates mixer performance as a function of the superconducting transition temperature (Tc). In th...

In this paper, a numerical study of a chaotic mixing process that involves a highly viscous fluid is presented. The investigated mixer is composed of two circular rods maintained vertically inside a cylindrical tank. The tank and the rods are heated and can rotate around their revolution axis. Chaotic flows are obtained by imposing a temporal modulation of the rotational velocity. Unsteady equa...

A radar transceiver operating at 1.56 THz has recently been developed to obtain coherent, fully polarimetric W-band (98 GHz) RCS images of 1:16 scale model targets. The associated optical system operates by scanning a small focused beam of sweptfrequency radiation across a scale model target to resolve individual scattering centers and obtain the scaled RCS values for the centers. Output from a...

Measurements of the frequency stability of a far-infrared molecular laser have been made by mixing the harmonic of an ultrastable microwave source with a portion of the laser output signal in a terahertz (THz) Schottky diode balanced mixer. A 3 GHz difference-frequency signal was used in a frequency discriminator circuit to lock the laser to the microwave source. Comparisons of the short- and l...

In this paper, a simple but effective method for compensation of the quadrature error in MEMS vibratory gyroscope is provided. The proposed method does not require any change in the sensor structure, or additional circuit in the feedback path. The mathematical relations of the proposed feedback readout system were analyzed and the proposed solution assures good rejection capabilities. Based on ...

The Listening Room at CCRMA, Stanford University is a 3D studio with 16 speakers (4 hang from the ceiling, 8 surround the listening area at ear level and 4 more are below an acoustically transparent grid floor). We found that a standard commercial digital mixer was not the best interface for using the studio. Digital mixers are complex, have an opaque interface and they are usually geared towar...

This work presents a detailed study of the graphene RF mixer in the ambipolar configuration, using quasi-free-standing epitaxial graphene on SiC. Record high conversion gain is achieved through use of optimized growth and synthesis techniques, metal contact formation, and dielectric materials integration. Hydrogen intercalation is utilized to isolate the graphene from the underlying SiC substra...

Radio transceivers capable of dynamic spectrum access require frequency agile transmitters with a clean output spectrum. High-Q filters are difficult to implement on chip and have limited tuning range. Transmitters with high linearity and broadband harmonic rejection can be more flexible and require less filtering. However, traditional Harmonic Rejection mixers suppress only a few harmonics. Th...

A coplanar millimeter wave doubler MMIC covering the entire G-band was developed. Based on a 50 nm metamorphic HEMT technology, the circuit demonstrates an output power of more than –12 dBm between 150and 220 GHz for an input power of 0 dBm. By increasing the input power to 12 dBm an output power exceeding 0 dBm was obtained in the frequency range between 180and 220 GHz. Good fundamental reject...

A self-heterodyne diode mixer is proposed using thin film process based on alumina substrate at 60 GHz in conjunction with grounded coplanar waveguide transition. To down-convert both very low RF and LO signals received simultaneously from transmitter for self-heterodyne communication scheme, the proposed mixer adapted with the knee voltage bias condition of 0.65 [V] improves its mixing efficie...