Low Conversion Loss Research Articles

Low Conversion Loss Mixers with Improved Finline Transition and Bandstop Filter

A Ka-Band hybrid integrated single-ended mixer with low conversion loss is designed in this paper. In the proposed circuit architecture, metallic via holes are implemented along the mounting edge of substrate embedded in the split-block of WG (waveguide)-finline-microstrip transition. Simulated results show that the effect of high-order modes due to the mounting groove is effectively eliminated and the transition loss is greatly improved. Meanwhile, a slow wave and bandstop filter at Ka band, which presents an equivalent short circuit, is designed for the maximized utilization of idle frequency energy, RF and LO signal energy. In this way, the conversion loss of the mixer can be further improved. The lowest measured conversion loss 3.52dB is obtained at 32.2 GHz; the conversion loss is flat and less than 5.68dB over the frequency band from 29 to 34 GHz.

Phase-Conjugated Arrays Using Low Conversion-Loss Resistive Phase-Conjugating Mixers and Stub-Loaded Patch Antennas

A 1-D four-element and 2-D eight-element phase-conjugated retrodirective arrays employing low conversion-loss resistive field-effect transistor mixers and stub-loaded patch elements are proposed. The mixer, systematically designed using a multi- harmonic loading technique, offers a low 5.2-dB conversion loss at a 4.5-dBm local oscillator power level. The stub-loaded patch element is a square patch with a capacitive open stub loaded at each of its four corners, leading to patch-size reduction, lower mutual coupling between adjacent elements, and broader beam width. With the same element spacing of half a free-space wavelength at 5.8 GHz, the mutual coupling is suppressed by 3.1 and 3.3 dB in the E- and if-planes, respectively, when compared to the conventional square patches. Within an angle of plusmn60deg normal to the arrays, distinct linearly polarized retrodirectivities in terms of pattern deformations are experimentally confirmed for both the H-plane of the 1-D array and both E- and H-planes for the 2-D array. Additionally, circularly polarized retrodirectivity are also experimentally confirmed for 2-D arrays.

An Improved Architecture of Sixth Subharmonic Mixers in E-Band

An improved architecture of sixth subharmonic mixers is proposed in this paper. In order to meet the need of low conversion loss, antiparallel diodes are selected and the length of four open/shorted microstrip stubs at both sides of the antiparallel diodes are carefully designed. For any important idle frequency components which can’t be reused by the four stubs, reactive terminations are presented by adjusting the length of main RF and LO microstrip. The tested results indicate the lowest conversion loss is 26.1 dB at the radio frequency of 72 GHz, with fixed LO at 12 GHz. The proposed circuit architecture is suitable for the implementation of subharmonic mixers in E-band as well as other millimeter and submillimeter-wave regions where high quality and high frequency LOs are difficult to realize.

Low conversion loss and high LO-RF isolation 94-GHz active down converter

We report a low conversion loss and high local oscillator (LO)-to-RF isolation 94-GHz monolithic-microwave integrated-circuit (MMIC) active down converter using 0.1-/spl mu/m InGaAs/InAlAs/GaAs metamorphic high electron-mobility transistor (MHEMT). The fabricated MMIC active down converter employs a one-stage MHEMT amplifier in the RF port of the active down converter, thereby amplifying the RF signal and improving the LO-to-RF isolation by using an inherent S/sub 12/ isolation characteristic. The fabricated MMIC active down converter shows an excellent conversion loss of 6.7 dB at an LO power of 10 dBm and high LO-to-RF isolations of 21 /spl plusmn/ 0.5 dB in a frequency range from 93.7 to 94.3 GHz. High dc and RF performances of the MHEMT used for the active down converter are due to the optimized epitaxial and device structure, and a maximum transconductance of 760 mS/mm, a current gain cutoff frequency of 195 GHz, and a maximum oscillation frequency of 391 GHz were measured. A active down-converter module is assembled by mounting the active down-converter chip on a jig with low-loss transition structure between the coplanar waveguide and waveguide. The fabricated active down-converter module shows a good conversion loss of 10.9 dB and a very high LO-to-RF isolation of 27.5 dB at 94.03 GHz.

High-performance 94-GHz single balanced mixer using 70-nm MHEMTs and surface micromachined technology

We reported 94-GHz, low conversion loss, and high isolation single balanced active gate mixer based on 70-nm gate length InGaAs/InAlAs metamorphic high-electron mobility transistors (MHEMTs). This mixer showed that the conversion loss and isolation characteristics were 2.5/spl sim/3.5 dB and under -29 dB in the range of 92.95/spl sim/94.5 GHz, respectively. The low conversion loss of the mixer is mainly attributed to the high-performance of the MHEMTs exhibiting a maximum drain current density of 607 mA/mm, an extrinsic transconductance of 1015 mS/mm, a current gain cutoff frequency (f/sub t/) of 330 GHz, and a maximum oscillation frequency (f/sub max/) of 425 GHz. High isolation characteristics are due to hybrid ring coupler which adopted dielectric-supported air-gapped microstrip line structure using surface micromachined technology. To our knowledge, these results are the best performance demonstrated from 94 GHz single balanced mixer utilizing GaAs-based HEMTs in terms of conversion loss as well as isolation characteristics.

High switching performance 0.1-/spl mu/m metamorphic HEMTs for low conversion loss 94-GHz resistive mixers

We report high switching performance of 0.1-μm metamorphic high-electron mobility transistors (HEMTs) for microwave/millimeter-wave monolithic integrated circuit (MMIC) resistive mixer applications. Very low source/drain resistances and gate capacitances, which are 56 and 31% lower than those of conventional pseudomorphic HEMTs, are due to the optimized epitaxial and device structure. Based on these high-performance metamorphic HEMTs, a 94-GHz MMIC resistive mixer was designed and fabricated, and a very low conversion loss of 8.2 dB at a local oscillator power of 7 dBm was obtained. This is the best performing W-band resistive field-effect transistor mixer in terms of conversion loss utilizing GaAs-based HEMTs reported to date.

Millimeter-Wave Broadband Mixers in New Testing and Measurement Instruments for High Data Rate Signal Analyses

The millimeter-wave (MMW) broadband mixers that are useful for measurement instruments to analyze MMW high data rate signals have been investigated. At first, we propose the specialized RF front-end for analyses of MMW high data rate signals. Next, the required specifications for the 1st mixers of the front-end are estimated, and the design, fabrication, and testing results of Q, V, and W-band monolithic broadband resistive mixers are described. The testing results are compared with performances of the diode mixer designed for V-band. It was found that the resistive mixers have very attractive performances of low conversion loss, good frequency flatness and high third order intercept point (IP3) with low Local (LO) oscillators power. The developed resistive mixers are suitable for the proposed MMW band measurement instruments.

A Very Low-Noise Integrated 3MM-Wave Schottky Diode Mixer and PHEMT IF Amplifier

An integrated 3mm-wave Schottky diode mixer and pseudomorphic high-electron-mobility transistor (PHEMT) IF amplifier with record noise performance at room temperature is described. The design has shown the room-temperature double-sideband (DSB) receiver noise temperature TRDSB of 190 K at 100 GHz due to a very low conversion loss in the full-height waveguide mixer and an ultra-low noise of the PHEMT IF amplifier. The receiver noise temperature has been reduced by a factor of 1.5 in comparison with the best previously reported 3mm-wave Schottky diode mixer receiver.

High Doping Density Schottky Diodes in the 3MM Wavelength Cryogenic Heterodyne Receiver

The paper describes a 3mm cryogenic mixer receiver using high doping density (“room-temperature”) Schottky diodes. The measured equivalent noise temperature Teq of the diodes is 109 K at 20 K, which is much higher than the Teq of the low doping density (“cryogenic”) diodes. In spite of this, the double-sideband (DSB) noise temperature of the cryogenic receiver developed is 55 K at 110 GHz, owing to the low conversion loss of the mixer and ultra-low noise of the PHEMT IF amplifier. This is the lowest noise temperature ever reported for a Schottky diode mixer receiver. The results obtained are useful for the development of submm receivers in which high doping density Schottky diodes are used.

Even-harmonic C-band modulator

Direct modulation at microwave frequencies promises the advantages of compact size, low cost, and relatively simple system design. In this paper, a novel architecture of a direct-vector C-band modulator is described. In particular, a subharmonic mixer is used to overcome the high carrier leakage that is associated with conventional fundamental modulators at microwave frequencies. The topology exhibits relative low conversion loss (11 dBc) and good image frequency rejection (23.5 dBc) and local oscillator (LO) rejection (23.9 dBc). The LO power level used by the mixer is approximately 6 dBm for optimal performance in the operating band.

Novel subharmonically pumped mixer incorporating dual-band stub and in-line SCMRC

A subharmonically pumped (SHP) mixer with very low conversion loss is proposed. The mixer employed the newly developed spiral compact microstrip resonant cell (SCMRC) and compact dual-band stub (DBS). Incorporating the in-line SCMRC and DBS into a second SHP mixer, we can provide proper terminations for the IF, RF, and local-oscillator (LO) signal simultaneously in addition to all major unwanted mixing products, leading to a unique low conversion-loss design. Our SHP mixer with a measured 3.9-dB single-sideband (SSB) down-conversion loss at 11.6-GHz RF signal outperforms typical designs of 8-12 dB, and represents a state-of-the-art performance for a planar X-band harmonic mixer. With a broad-band operation, our mixer shows an SSB down-conversion loss of less than 8.2 dB from 9 to 12.8 GHz. Moreover, the measured LO-RF isolation is better than 45 dB for LO frequency ranges of 4-5.8 GHz. Large-signal two-tone measurements reveal an excellent linear response of the working prototype, showing 7.5 dBm and 52 dB for the 1- dB power compression point and spurious-free dynamic range, respectively.

High performance quadruple sub-harmonic mixer for millimeter-wave applications

In this paper, we present high performance quadruple sub-harmonic mixers for millimeter-wave applications. The sub-harmonic mixer was designed by using 0.1 μm GaAs PHEMT's and the coplanar wave-guide library. We show the low conversion loss of 5.8dB at a local oscillator (LO) power of 13dBm from the fabricated sub-harmonic mixers. The V-band sub-harmonic mixer also ensure a high degree of isolation showing −75.0dB in the LO-to-IF and −48.1dB in the LO-to-RF at a frequency of 14.5GHz, respectively. The fabricated V-band sub-harmonic mixer has a lower conversion loss characteristics compared with ever reported mixers for millimeter frequencies.

Application of CAD load‐pull techniques in mixer design

AbstractThis work describes the application of a commercial CAD software to implement load‐pull techniques in the design of microwave mixers. This method is used to generate conversion‐loss regions when a diode is pumped and operated as a mixer circuit. Emphasis is placed on the inclusion of image and out‐of‐band terminations to optimize the operating conditions required to obtain low conversion loss. An X‐band 5‐dB conversion‐loss mixer is designed and tested using this method. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 320–323, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10754

Optical mixing of microwave signals in a nonlinear semiconductor laser amplifier modulator

In this paper we propose and evaluate the optical mixing of RF signals by means of exploiting the nonlinearity of a SLA modulator. The results show the potential for devices with low conversion losses (and even gain) and polarization insensitivity and reduced insertion losses.

94/47-GHz regenerative frequency divider MMIC with low conversion loss

A coplanar regenerative frequency divider monolithic microwave integrated circuit (MMIC) based on 0.15-/spl mu/m pHEMTs on GaAs for 94/47-GHz frequency conversion has been developed, achieving a bandwidth of 23% for stable division. A very low conversion loss of 2.5 dB was obtained with an input level of -2 dBm and a dc power consumption of 8 mW, without using additional buffer amplifiers. The frequency of operation can be tuned by a varactor diode in the feedback network over a 2.5-GHz range to compensate for technology variations. Various methods for the simulation of stable and unstable operation and bandwidth and conversion performance are presented, using accurate modeling of the active and passive components.

Efficient photonic mixer with frequency doubling

A photonic mixer can upconvert/downconvert the signal in a fiber link to replace a conventional electronic mixer. We demonstrate a photonic mixer with frequency doubling that can be driven by half the intermediate frequency with low-cost microwave and optical components. The photonic mixer has a conversion loss of about 3.2 dB, which is the lowest conversion loss ever reported.

Jet Propulsion Laboratory/NASA Lewis Research Center space qualified hybrid high temperature superconducting/semiconducting 7.4 GHz low-noise downconverter for NRL HTSSE-II program

A deep space satellite downconverter receiver was proposed by Jet Propulsion Laboratory (JPL) and NASA Lewis Research Center (LeRC) for the Naval Research Laboratory's (NRL) high temperature superconductivity space experiment, phase-II (HTSSE-II) program. Space qualified low-noise cryogenic downconverter receivers utilizing thin-film high temperature superconducting (HTS) passive circuitry and semiconductor active devices were developed and delivered to NRL. The downconverter consists of an HTS preselect filter, a cryogenic low-noise amplifier; a cryogenic mixer, and a cryogenic oscillator with an HTS resonator. HTS components were inserted as the front-end filter and the local oscillator resonator for their superior 77 K performance over the conventional components. The semiconducting low noise amplifier also benefited from cooling to 77 K. The mixer was designed specifically for cryogenic applications and provided low conversion loss and low power consumption. In addition to an engineering model, two space qualified units (qualification, flight) were built and delivered to NRL. Manufacturing ,integration and test of the space qualified downconverters adhered to the requirements of JPL class-D space instruments and partially to MIL-STD-883D specifications. The qualification unit has /spl sim/50 K system noise temperature which is a factor of three better than a conventional downconverter at room temperature. Commercial applications such as intersatellite links and V-SATS are envisioned to benefit by >3 dB link margin, or a factor of 2 in antenna size, from a future hybrid HTS/semiconducting cryogenic receiver employing new InP based HEMT LNA. In a spread spectrum communication network, the number of users per beam would more than double.

A fiber optic/millimeter-wave radio transmission link using HBT as direct photodetector and an optoelectronic upconverter

The performance of a fiber optic subcarrier link using an HBT as a direct photodetector and an optoelectronic up-converter in 50 GHz band has been experimentally investigated at a wavelength of 0.83 /spl mu/m. From comparison with the performances of links using other MMIC-compatible photodetectors and with that of a high speed PIN-photodetector, this paper shows that the HBT-photodetector is superior to the other MMIC compatible photodetectors (MSM and HEMT). It is also shown that HBT not only has a high photodetection ability in the millimeter-wave band but also provides low conversion loss between a microwave subcarrier modulated by an optical signal and a millimeter-wave carrier. Also demonstrated are video FM-subcarrier transmission and 140 Mbps QPSK digital radio transmission using an HBT optical/RF transducer. At transducer transmission power of around -20 dBm, the HBT optical/RF transducer allows 50 GHz band radio transmission over optical fiber to achieve a weighted SNR of more than 50 dB and a data rate of 140 Mbps in indoor application.

A novel general approach for the optimum design of microwave and millimeter wave subharmonic mixers

The design of subharmonic mixers is complicated and involves separation of signals and application of correct loading at the important idler frequencies. In this paper we present a novel general approach, which enables the designer to establish the optimum loading conditions for the different signals to get low conversion loss and good matching simultaneously. The method is demonstrated by a design example using a 30 GHz X2 subharmonic mixer. In this example it is shown that a nonoptimal design can yield conversion loss of up to 13.5 db, while an optimal design yields a conversion loss of 3.6 db.

A W-band monolithic, singly balanced resistive mixer with low conversion loss

We report the design, measured and simulated performance of a novel W-band monolithic, singly balanced resistive FET mixer utilizing 0.1-μm pseudomorphic AlGaAs/InGaAs on GaAs HEMT technology. At an LO drive of +8 dBm, this mixer has exhibited a minimum measured conversion loss of 12.8 dB, nearly a 10 dB improvement over previously reported data in this frequency range. Furthermore, the mixer figure of merit, defined as P/sub 1-dB,in/-P/sub LO/, is at least +2 dBm, which is nominally 6 dBm better than that of comparable diode mixers at W-band. These results indicate the excellent potential of this mixer for integration with other circuit components in fully monolithic subsystems.