This paper describes numerical analyses of resistive mixer operation, followed by measured performances of a V-band (50 - 75 GHz) monolithic InP HEMT resistive mixer operable with a very low LO power. Our model assumes that the channel conductance of the InP HEMT can be described by three linear functions according to the applied gate voltage. The calculated results obtained with the model have shown that the LO power level required for mixer operation is determined by the gate bias voltage and that a device with abrupt conductance shifts is suited to low LO power operation for a resistive mixer. It is also shown that conversion loss saturation of a resistive mixer is caused by its channel conductance saturation. A V-band monolithic resistive mixer has been designed and fabricated using Coplanar Waveguides (CPW) and a 0.15 mm InP HEMT with abrupt channel shifts. Good agreement between measured and simulated conversion losses are obtained. A minimum conversion loss of 8.4 dB is achieved at the 55 GHz RF-frequency and the -2 dBm LO power. It also exhibits an excellent IF output linearity to allow the 1 dB compression RF input level to be comparable with LO power, indicating good intermodulation performance. It is demonstrated that the proposed simple model of the channel conductance can easily calculate conversion characteristics of a resistive mixer with high accuracy.

This paper presents a review of the techniques and models that can be used for the noise performance calculation of active devices under linear and nonlinear operations. In a first part, the modeling techniques and the noise models of FETs, HEMTs, BJTs and HBTs are described. In the second part, a generalization of the impedance field method for the noise modeling in devices under nonlinear periodic operation is proposed. This method can be used for the modeling of microwave and millimeter wave mixers and oscillators.

This paper describes the distortion characteristics of an even harmonic type direct converter (EH-DC) used in earth stations for CDMA satellite communications. Direct conversion technique is known as a method to simplify circuit topologies of microwave transceivers. In satellite communications, multi carriers which have high and nearly equal level are provided to a quadrature mixer of the EH-DC. Hence, the third-order intermodulation degrades receiving characteristics. In this paper, we show the relationship between the distortion characteristics and noise figure of the EH-DC for CDMA satellite communication systems. Furthermore, we show NPR of even harmonic quadrature mixers caused by the third-order intermodulation. Experimental results in X-band indicate that the proposed EH-DC has almost the same BER characteristics compared with a heterodyne type transceiver.

We have demonstrated the single-chip RF front-end GaAs MMIC for the Japanese Personal Handy-phone System. It has a high efficiency HPA, a T/R switch, a LNA and a low-distortion down converter mixer. The IC employs a negative voltage generator for use of single voltage DC power supply. The HPA provides an output power of 21.5 dBm, with an ACPR of 55 dBc and an efficiency of 35%. The LNA has a noise figure of 1.6 dB and a gain of 14 dB with current of 2.3 mA. The newly developed active cascode FET mixer has a high IIP3 of 1 dBm with a high conversion gain of 10 dB and low consumption current of 2.3 mA. The IC is characterized by high performance for RF front-end of PHS handheld terminals. The IC is available in a 7.0 mm6.4 mm1.1 mm plastic package.

Millimeter- and submillimeter-wave low-noise superconducting receivers, such as superconductor-insulator-superconductor (SIS) mixers, hot-electron bolometer (HEB) mixers, and superconducting direct detectors, are addressed in this paper. Some general topics on the development of SIS mixers, including SIS junction and integrated tuning circuitry, mixing circuitry, and mixer-performance simulation, are extensively discussed. A tuneless waveguide SIS mixer developed at Nobeyama Radio Observatory (NRO) and its performance are presented. The fundamental mechanisms of diffusion- and phonon-cooled HEB mixers and recent advances in HEB mixers are briefly reviewed. Finally, incoherent detectors with superconducting tunnel junctions are discussed. Results for a direct detecting experiment at 500 GHz are given.

We report on progress in the development of high-current-density all-NbN tunnel junctions for application as submillimeter wave SIS mixers. A very high current density up to 54 kA/cm2, roughly an order of magnitude larger than any reported results for all-NbN tunnel junctions, was achieved in the junctions with a thin aluminum nitride (AIN) tunnel barrier. Even though the junctions have a very high current density, they showed high-quality junction characteristics with a large gap voltage, sharp quasipartical current rise, and small subgap leakage current. The junctions also exhibited good Josephson tunneling behavior, excellent terahertz response, and sensitive heterodyne mixing properties. NbN/AIN/NbN tunnel junctions were integrated with a NbN thin-film antenna to investigate the terahertz responses and the heterodyne mixing properties in a quasioptical mixer testing system. Photon-assisted tunneling steps were clearly observed on the I-V curve with irradiation up to 1 THz, and low-noise heterodyne mixing was demonstrated in the 300-GHz band.

A 90 GHz band planar-type superconducting mixer using Ba1-xKxBiO3 (BKBO) bicrystal junctions was fabricated on a MgO bicrystal substrate. The mixer is integrated with microwave circuits and two junctions, but we could not operate the mixer in image rejection mode because of process damage to the junction properties. However we confirmed the mixing operation; the intermediate frequency (IF) signal was observed up to 17K (LO87 GHz, RF92 GHz).

A V-band compact monolithic up-converter and down-converter were designed and tested. Each frequency converter was highly integrated with RF and LO amplifiers into a single compact chip. To avoid undesirable resonance, the chip width was limited to 0.9 mm. The up-converter has a balanced configuration to suppress undesired LO leakage. Using the uniplanar concept, the chip size of each frequency converter was greatly reduced to only 2.6 mm2. Measured performance of the up-converter includes conversion gain of-10.6 dB3.3 dB for a bandwidth of 10 GHz, and LO leakage is more than 10 dB below LO input. The down-converter shows a conversion gain of -0.4 dB2.0 dB.

We have developed a strato-mesospheric ozone monitoring system with a low noise SIS mixer, which receives 110.836 GHz millimeter-wave emission due to the rotational transition of ozone molecules (J=61,560,6). The system is completely standalone. We derived the altitude profile of ozone density between 25 km and 80 km from the observed spectrum. The receiver noise temperature was as low as 17 K (DSB), so that the altitude profile could be obtained every 3-10 minutes. The monitoring system can operate continuously over one year without any maintenance work, because it utilizes a 4 K closed cycle helium refrigerator and reliable Nb/AIOx/Nb SIS junctions. We used two acousto-optical spectrometers (AOSs) as real-time spectrometers because of their high resolution and simple construction. In an up-to-date system, one AOS would have a band-width of 65 MHz and the other, a band-width of 250 MHz with resolutions of 40 kHz and 250 kHz, respectively. A computer controls the entire system and is also used to analyze measured data. In this paper, we present the principles of system operation, the latest performance and the construction of the system, and some observed data.

A quasi-optical Superconductor-Insulator-Superconductor (SIS) mixer has been designed and tested in the 270-GHz band. The mixer used a substrate-lens-coupled log-periodic antenna and a tuning circuit for RF matching. The antenna is planar and self-complementary, and has a frequency-independent impedance of around 114 Ω over several octaves. The tuning circuit consists of two Nb/AIOx/Nb tunnel junctions separated by inductance for tuning out the junction capacitances and a λ/4 impedance transformer for matching the resistance of the two-junction circuit to the antenna impedance. The IF output from the mixer is brought out in a balanced method at each edge of the antenna, and is coupled to a low noise amplifier through a balun transformer using a 180-degree hybrid coupler for broadband IF matching. Double sideband receiver noise temperatures, determined from experimental Y-factor measurements, are about 150 K across the majority of the desired operating frequency band. The minimum receiver noise temperature of 120 K was measured at 263 GHz, which is as low as that of waveguide receivers. At this frequency, measurement of the noise contribution to the receiver results in input losses of 90 K, mixer noise of 17 K, and multiplied IF noise of 13 K. We found that the major sources of noise in our quasi-optical receiver were the optical losses.

Here we report on a fabrication and a millimeter-wave performance of reliable and reproducible high-Tc superconducting (HTS) Josephson junctions on MgO substrates using a focused Ga ion beam (FIB). The junction normal resistance Rn can be controlled by making the junction in a series. The Rn depends on space between each junction in the series structure. A mechanism of the junction is proposed by measuring cross-sectional transmission electron microscopy (TEM) images and their X-ray spectra of Ga, Y, Ba, Cu, Mg and O. The junctions with more than 1 µm spaces, and flat and lateral structure are independent each other for the crystallization process. We observe the HTS mixer-antenna performance as fundamental/harmonic mixers in the wide frequency range up to 100 GHz.

This paper proposes a novel architecture and MMICs for an integrated 2-32 GHz front-end of a spectrum analyzer. The architecture achieves miniaturization by eliminating the large YIG tracking filter and also achieves multi-octave measurement with less than one octave sweep of the first local oscillator. The MMIC's demonstrate ultra-wideband performances with reduced chip sizes by utilizing newly developed FET cells for power combination, multi-order frequency conversion, low leakage variable resistance, and active impedance translation. The MMIC's are a fundamental/harmonic frequency converter, a variable attenuator, a single-pole triple-throw switch, a single-pole double-throw switch, a distributed pre-amplifier, and an active LC lowpass filter. All the MMIC's are smaller than 1 mm2, except the pre-amplifier and the filter.

A Superconductor-Insulator-Superconductor (SIS) mixer using two junctions connected in parallel through a stripline inductance has been studied. The essential point of the two-junctions device is that the capacitance of the junctions was tuned out by the inductance to obtain a broadband operation without mechanical tuning elements. It has been shown by theoretical analysis that the performance of this type of device is excellent and nearly quantum-limited performance of the mixer can be obtained. It has been demonstrated that the double sideband (DSB) noise temperature of a receiver employing this type of device was less than 40 K over the bandwidth of 90-120 GHz and that the lowest receiver noise temperature of 18 K, which is only 3.2 times as large as the quantum limited photon noise was obtained around 118 GHz. Junctions used in the two-junctions device have significantly larger area, i.e. larger capacitance, and smaller normal resistance than conventional ones. In order to obtain a good impedance match between the source and the junctions, an impedance transformer made of a superconductiong stripline was integrated with the junctions. This type of two-junctions device can easily be scaled to submillimeter frequency without using submicron-sized SIS junctions.

This paper discusses the development of a monolithic image-rejection mixer with very wide-band (about 60% of the center frequency) image rejection characteristics for 16-QAM digital microwave radio communication receivers. The mixer can be commonly used in 4-, 5-, and 6-GHz bands, which reduces the cost. The mixer consists of a wide-band 90splitter, in-phase divider and drain LO injection mixers. They are designed on a single 2.81.8 mm2 GaAs chip based on a uniplanar MMIC lumped-constant element technique. The mixer achieved an image rejection ratio of greater than 25 dB and a conversion loss of less than 2 dB at a wide LO frequency range from 3.5 to 6.5 GHz, without consuming any DC power.

The performance of a traveling wave Mach-Zehnder external optical modulator (EOM) mixer is described and compared with a conventional diode mixer's performance. Additionally, by incorporating external circuitry, the EOM mixer can provide single sideband suppression in addition to the inherent local oscillator suppression. The basic frequency mixing function of the EOM mixer is first described theoretically and then extended to the sideband suppression case. The performance of both configurations is also presented. Achievable electrical isolation between LO (carrier) and RF (upconverted data signal at LOIF) frequencies is greater than 95 dB and total link conversion loss is 37 dB in this demonstration with a laser diode source. Sideband suppression of greater than 43 dB with respect to the desired sideband at the photodetector output is achieved.

Thin-film YBCO Josephson junctions were successfully fabricated by a pulsed excimer laser ablation, and the mixing experiments in the microwave region (820 GHz) were carried out at the temperature of 77 K. The IF output maximum was obtained at the bias voltage midway between the zero and the first Shapiro steps for the fundamental mixing. For the 2nd harmocic mixing, the IF output maximum was obtained at a zero bias voltage, and the conversion efficiency was -14 dB at the microwave frequency of 18 GHz. These results strongly suggest that the fabricated thin-film Josephson junctions work well at the temperature of 77 K as detectors and mixers in the microwave regions (820 GHz).

This paper proposes an MMIC image rejection mixer and an MMIC balanced mixer employing multilayer microstrip lines and high-electron-mobility-field-effect-transistor (HEMT)s with a LUFET configuration (line-unified HEMT module). The advantage of the mixers is remarkable chip size reduction by the combination of the two technologies. The multilayer microstrip line, in which one microstrip line is placed upon another, is used for stacking passive circuits, e.g. a 90 hybrid and distributed lines, to reduce the chip-area occupied by transmission lines, and to allow flexible line allocation. The line-unified HEMT module provides all functions required for in-phase/out-of-phase power divider/combiners in HEMT electrode and unified coplanar lines configuration. A 29-32 GHz image rejection mixer and a 3-27 GHz balanced mixer are realized in only 1.6 mm 1.0 mm and 1.8 mm 1.2 mm MMIC chip size, respectively.