Seng-Woon Chen

A W-band integrated power module using MMIC MESFET power amplifiers and varactor doublers

A high-performance integrated power module using U-band MMIC MESFET power amplifiers in conjunction with W-band MMIC high efficiency varactor doublers has been developed for millimeter-wave system applications. The authors present the design, fabrication, and performance of this W-band integrated power module. Measurement results show an output power of 90 mW with an overall associated gain of 29.5 dB at 94 GHz. A saturated power of over 95 mW was also achieved. These results represent the highest reported power and gain at W-band using MESFET and varactor frequency-doubling technologies. This integrated power module is suitable for future 94-GHz missile seeker applications. >

U-band MMIC HBT DRO

A 46.3 GHz dielectric resonator stabilized oscillator (DRO) using AlGaAs/GaAs heterojunction bipolar transistor (HBT) and monolithic microwave integrated circuit (MMIC) technology has been designed, fabricated, and characterized. The oscillator exhibits 2.6 dBm output power with 5.8% dc-to-RF efficiency and less than /spl minus/132 dBc/Hz phase noise at 5 MHz offset from the carrier. To our knowledge, this is the highest frequency oscillator ever reported using HBT devices and MMIC technology. >

A high-performance 94-GHz MMIC doubler

A 94-GHz monolithic microwave integrated circuit (MMIC) frequency doubler with 25% efficiency and 65-mW output power has been developed. Variations in the Schottky barrier varactor diodes performance as a doubler with its geometry and doping profile were analyzed for optimum efficiency and output power. Optimum doubler performance was obtained as a consequence of use of the optimized diode parameters resulting from this analysis. Measured results of the diode parameters as well as the doubler response showed excellent agreement with the analysis. The doubler exhibits better performance than those reported in the literature at similar frequencies using an MMIC approach. >

Tunable, temperature-compensated dielectric resonators and filters

A thermal and electromagnetic model of a tunable hybrid-mode dielectric double resonator is introduced and analyzed by the mode-matching technique. Results of the analysis show the temperature sensitivity of the structure as a function of the center frequency as well as the other resonator parameters. A simple optimization procedure which allows the design of the resonator to have both a wide tunability range and good thermal stability of the resonant frequency is described. A circuit model is presented for a tunable four-pole dual-mode filter. The model exhibits interesting dual passbands, separated by a very-high-attenuation stopband. Measured results obtained from an experimental four-pole dual-mode dielectric resonator filter designed using the tunable hybrid-mode resonators showed excellent tunability range (200 MHz at C-band) and good agreement with the circuit model. >

A novel coupled method for dual-mode dielectric resonators and waveguide filters

A novel method for coupling dual-mode waveguide or dielectric resonator cavities is described and analyzed. The method has advantages of providing a practical, flexible, economic means of replacing irises, of offering easy tunability of the coupling over a wide range of coupling values, and of reducing the length of the coupling structure. Calculation of the resonators coupling parameters using the mode-matching method yields accurate results and is verified by measurements. Experimental four-pole dual-mode elliptic function filters using the coupling method for empty cavities and dielectric-resonator-loaded cavities were constructed and tested. The test results showed excellent agreement with theoretical analysis. >

A Unified Design of Dielectric Resonator Oscillators for Telecommunication Systems

A unified design approach for improving the performance of both regular DRO & Voltage Tuned DRO (VTDRO) is presented with a step-by-step procedure. The novel designs of 23GHz DRO and 18GHz VTDRO are reported together with their experimental results showing superior performance over the previously published results; for example, the frequency- temperature stability at 23GHz has been improved by a factor of four, while the frequency tuning sensitivity at 18GHz by a factor of five.

Rigorous analysis and design of a high-performance 94 GHz MMIC doubler

A 94-GHz monolithic microwave integrated circuit (MMIC) frequency doubler with 25% efficiency and 65-mW output power is discussed. Variations in the Schottky-barrier varactor diodes performance as a doubler with its geometry and doping profile are analyzed for optimum efficiency and output power. Optimum doubler performance is obtained by use of the optimized diode parameters resulting from this analysis. Measured diode parameters as well as doubler responses show excellent agreement with the analysis. >

Role of complex modes in modeling discontinuities of dielectric loaded waveguides

It is shown that modeling of step discontinuities in cylindrical dielectric loaded waveguides excited in hybrid modes using mode matching cannot converge unless complex modes are included in the field expansions. If the parameters of the structure and operating frequency allow the existence of complex modes, then the purely propagating and purely evanescent mode fields are not a complete set, unless complemented by the complex mode fields.<<ETX>>

Rigorous design of a 94 GHz MMIC doubler

A 94-GHz monolithic microwave integrated circuit (MMIC) frequency doubler with 25% efficiency and 65 mW output power is discussed. Variation in the diodes performance as a doubler with its geometry and doping profile are analyzed for optimum efficiency and output power. Optimum doubler performance is obtained by use of the optimized diode parameters resulting from this analysis. Measured results of the diode parameters as well as doubler response show excellent agreement with the analysis. The doubler exhibits better performance than those reported in the literature at similar frequencies using an MMIC approach.<<ETX>>

A novel coupling method for dual mode waveguide or dielectric resonator filters

A novel method for coupling dual-mode waveguide or dielectric resonator cavities is described and analyzed. The method provides a practical, flexible, economic means of replacing irises, and it offers easy tunability of the coupling over a wide range of coupling values. Calculation of the resonators coupling parameters using the mode matching methods yields accurate results and is verified by measurements. An experimental X-band four-pole dual mode elliptical function waveguide cavity filter using the coupling method was constructed and tested. The test results show excellent agreement with theory.<<ETX>>