a numerical model for simulating residence time distribution (rtd) of turbulent flows in helical static mixers is proposed and developed to improve the understanding of static mixers. the results of this model is presented in terms of different volumetric flow rate to illustrate the complicated flow patterns that drive the mixing process in helical static mixers. the computed results are also u...

The wireless communications market has grown substantially during the last decade. Recent advances in wireless technology have reduced the size and cost of mobile radios while improving performance. The increasing level of integration in wireless circuits has led to many of these improvements. However, increased integration is dependent on the development of novel transceiver architectures that...

The impedance of the superconducting hot-electron bolometer mixer was measured in the range 0.2-4 GHz. A special technique relying on determination of the Sz, transmission parameter of the device was used. Many advantages of the technique (wide frequency range, in situ calibration, low test power, accuracy) are demonstrated. The estimate of the mixer bandwidth from the impedance data using the ...

The performance of quasi-optical (QO) SIS mixers designed for operation around 1 THz is evaluated. Mixers incorporating Si elliptical lens with either double slot-line or double dipole antennas with back reflectors have been fabricated and measured. Nb/AlAlOx/Nb superconductor-insulator-superconductor (SIS) tunnel junctions are integrated with a NbTiN-SiO2-Al microstrip circuit to tune out the ...

This paper aims to introduce a quadrature VCO (voltage control oscillator) which applies superharmonic coupling. The presented quadrature VCO is suitable to be used, both with 2 × subharmonic mixers, as well as 4× subharmonic mixers. It would be impossible to avoid the presence of harmonics in CMOS VCO circuits. These harmonics are in general, undesirable signals which tend to accompany the des...

An analysis is presented for the conversion loss and noise of microwave and millimeter-wave mixers. The analysis includes the effects of nonlinear capacitance, arbitrary embedding impedances, nonideality of microwave diodes, and shot, thermal, and scattering noise generated in the diode. Correlation of downconvertd components of the time-varying shot noise is shown to explain the “anomalous” no...

An overview of monolithic radio-frequency (RF) active mixer design is presented. The paper is divided into two parts. The first part discusses the performance parameters that are relevant to the design of downconversion mixers, and how they affect the system performance. The second part presents three common kinds of mixer topologies, namely, unbalanced, singlebalanced, and double-balanced desi...

The two signals inserted into the two input ports are usually the Local Oscillator signal, and the incoming (for a receiver) or outgoing (for a transmitter) signal. To produce a new frequency (or new frequencies) requires a nonlinear device. In a mixing process if we want to produce an output frequency that is lower than the input signal frequency, then it is called down-conversion and if we wa...

Micromixing is a crucial process within microfluidic systems such as micro total analysis systems (μTAS). A state-of-art review on microstructured mixing devices and their mixing phenomena is given. The review first presents an overview of the characteristics of fluidic behavior at the microscale and their implications in microfluidic mixing processes. According to the two basic principles expl...

A planar active retrodirective four-element array with subharmonic phase conjugation mixers based on anti-parallel diode pairs (APDPs) is proposed. As compared to previous phase conjugation mixers using twice RF frequency for LO frequency, the proposed conjugation mixers need only half RF frequency so that it can be easily applied for millimeter-wave applications. Receive, transmitting, local o...