Michael Sterns

Design and Fabrication of Broadband Hybrid GaAs Schottky Diode Frequency Multipliers

Frequency extender modules of vector network analyzers and signal generators, as well as front-end modules of semiconductor automatic test systems, make use of broadband resistive diode frequency multipliers. This paper presents the design and fabrication of innovative planar varistor frequency multipliers. Three frequency triplers (#1, #2, #3) and two frequency doublers (#4, #5), operating in the 60-110 GHz and 50-110 GHz frequency ranges, respectively, are designed. The hybrid architecture utilizes commercial gallium arsenide Schottky diodes from United Monolithic Semiconductors on thin-film processed high-permittivity alumina substrate. Synthesis is based on a co-simulation procedure between 3-D electromagnetic field and nonlinear harmonic balance circuit simulations. Scalar and spectral measurement data over the focused output frequency ranges are presented. Conversion loss values around 18 dB from 60 to 95 GHz and below 22 dB from 60 to 110 GHz are achieved with frequency tripler #1. Frequency doubler #5 achieves conversion loss values below 15 dB from 50 to 89 GHz and below 22 dB from 50 to 110 GHz. A comprehensive comparison of the presented work with reported frequency multipliers is included.

Novel tunable hexaferrite bandpass filter based on open-ended finlines

In this paper a novel tunable bandpass filter based on open ended finlines is presented. Hexagonal ferrite spheres are used as resonators to cover a tuning frequency range from 39GHz to 68GHz. The measured insertion loss of the filter varies from 5.3dB to 7dB with a typical 3dB-Bandwidth between 300MHz and 400MHz. An off-resonance isolation of about 60dB is achieved although only two spheres are used.

Novel coupled microstrip wideband filters with spurious response suppression

Wideband coupled line filters with spurious response suppression (2/0) in the millimeter wave range are reported. The first filter exhibits a relative bandwidth of 62% with a return loss better than 20 dB and a suppression of the second spurious passband of more than 40 dB. The very high necessary couplings to achieve that large bandwidth in combination with the spurious suppression are realized by removing partially the ground metallization beneath the proposed coupling sections. The filters are directly compatible to microstrip circuits without the need for complicated transitions. They do not require techniques like substrate suspension or dielectric overlay to match the even- and odd-mode phase velocities, but are realizable on a classical substrate with ground. Further, simulation and measurement results of a second, high selective filter (11th order) with an even higher bandwidth of 78% are shown. Measurement and simulation results are fitting very well.

A hybrid broadband millimeter-wave diode ring mixer with advanced IF extraction technique

We report on a hybrid octave-bandwidth millimeter-wave diode mixer with advanced IF extraction. The design uses a reproducible, low cost hybrid technology including thin- film circuit and flip-chip mounted diode chips. Side coupled Marchand baluns with IF tap provide balanced RF and LO signals as well as serve for extracting the IF signal. Measurement results for fixed, low IF frequency show a conversion loss around 10 dB from 35 to 67 GHz. Furthermore the mixer is suitable for IF frequencies up to 23 GHz. These features allow very flexible applications of the presented mixer in broadband test and measurement systems.

A quasi-lumped ultra-broadband contiguous SSL-diplexer from DC to 80 GHz

A contiguous planar diplexer in suspended stripline technology with ultrawideband channels from DC to 40 GHz and 40 GHz to 80 GHz is presented. The design of the diplexer is based on quasi-complementary LC lowpass and highpass prototypes which are directly transformed into transmission line elements by using a quasi-lumped approach. This very straightforward design procedure requires no susceptance annulling networks and no introduction of unit elements which could limit the diplexers operation bandwidth. For achieving an optimal compatibility with external circuits, an ultra-broadband SSL-MSL (suspended stripline - microstrip line) transition with a return loss of more than 18 dB from DC to 83 GHz was designed. The realized diplexer is extremely compact (6×4.5mm) and features a return loss of more than 12 dB from DC to 81 GHz with very low channel insertion losses of typically less than 1 dB after proper optimization.

Novel tunable hexaferrite bandpass filter based on rectangular waveguide coupled shielded coplanar transmission lines

In this paper a novel tunable high isolation bandpass filter is presented. The filter consists of two shielded coplanar transmission lines coupled by a rectangular waveguide. Hexagonal ferrite spheres are used to cover a tuning frequency range from 50 to 80GHz. Measurement results up to 69GHz are shown. The measured insertion loss of the filter lies between 7.1 and 9.3dB. An off-resonance isolation better than 60dB is achieved what is extraordinarily high for a two spheres filter. The typical 3dB-bandwidth is about 250MHz. As planar transmission lines are used, the filter can be integrated into a coplanar or microstrip environment easily what is advantageous for the construction of highly integrated modules. The operating frequency range can be expanded up to 80GHz by replacing the 1.85mm-connectors by 1mm-connectors or using other suitable waveguide transitions, thus covering considerably more bandwidth than rectangular waveguide based coupling structures.

A novel DGS-Marchand balun from 40 to 80 GHz with IF-tap for mixer design

Novel wideband planar Marchand baluns in the millimeter wave range from 40 to 80 GHz are presented. The circuits can be fabricated in a regular thin-film process due to less stringent specifications by using defected ground structure (DGS) technology. The return loss of the balun is better than 10 dB from 40 -80 GHz and better than 15 dB from 43-73 GHz. The amplitude balance is better than 2 dB from 40-80 GHz and better than 0.5 dB from 43-73 GHz. The phase balance error is smaller than 8deg over the entire frequency range. Simulation and measurement results are fitting very well. Several additional versions of the proposed balun are presented providing IF-paths to build a complete double-balanced mixer circuit. To show the applicability of the baluns, a low cost hybrid ring mixer for an IF of 500 MHz has been fabricated. Measurement results show a flat conversion loss of about 9 dB from 33 -69 GHz. Further measurement results for a second mixer for IF frequencies up to 23 GHz are presented.

An Octave-Bandwidth Double-Balanced Millimeter-Wave Mixer

The paper reports on an octave-bandwidth double-balanced mixer which operates in the millimeter-wave range from 35 to 70 GHz. The design uses a low cost hybrid technology: A thin-film circuit is fabricated on an alumina substrate, and the diodes are flip-chip mounted. Balanced signals are provided by side coupled Marchand baluns. As a result the conversion loss averages out at 13 dB