Single-sideband Conversion Loss Research Articles

170 GHz quasi-optical sub-harmonic mixer with a back-to-back lenses packaging based on HDI.

The paper presents a 170 GHz quasi-optical sub-harmonic mixer with a 3D-printed back-to-back lenses packaging. The quasi-optical mixer is comprised by a pair of antiparallel GaAs Schottky diodes, a patch antenna for receiving local oscillator (LO) pump signal, a symmetric-slit patch antenna for receiving radio frequency (RF) signal, dual 3D-printed lenses and a matching network. The quasi-optical mixer with a pair of antiparallel GaAs Schottky diodes is designed on a multilayer build-up printed circuit board (PCB) utilizing commercially low-cost and high-density interconnect (HDI) technology. The LO and RF antennas are placed on the front and back of the multilayer build-up substrate, respectively, thus significantly simplifying the quasi-optical design. Furthermore, dual 3D-printed lenses placed back-to-back are proposed for LO and RF antennas radiation gain enhancement and mechanical robustness. Additionally, the buried planar reflectors in the substrate maintain effective radiation isolation between the antennas. For facilitating coupling efficiency of signal power into the Schottky diodes and signal isolation between the LO pump signal and RF signal, a compact matching network with low-loss quasi-coaxial via transition structure is integrated in the mixer circuit. The measured single-sideband conversion loss is from 11.3 to 15.4 dB in an operation range of 160 to 180 GHz. The measured radiation patterns agree well with the simulated results.

A Novel 180–210 GHz Single Sideband Mixer Using Filtering Waveguide-Microstrip Transition Structure

In this letter, we proposed a novel 180–210 GHz single sideband (SSB) Schottky diode-based subharmonic mixer (SHM), which features in simpler structure and fabrication compared with existing methods. Image rejection of the 220–250 GHz upper sideband (USB), as well as impedance matching, was achieved by a filtering waveguide-microstrip transition structure at the radio frequency (RF) input, rather than using traditional waveguide filters. Eventually, the mixer was measured to show great performance, including a SSB conversion loss (CL) of 8–12 dB across the passband, and an image rejection ratio (IRR) of 15–35 dB.

A Novel 183 GHz Solid-State Sub-Harmonic Mixer

This paper proposes a novel sub-harmonic mixing topology. Based on the proposed topology and the precise three-dimensional electromagnetic model of the Schottky barrier diode; a novel 183 GHz solid-state sub-harmonic mixer is designed and measured. By adding a compact low-pass filter near the ground of the mixer’s circuit, the effect on the mixer’s RF performance of the random error of the conductive adhesive in assembling is effectively decreased. The test results show that the optimal single-sideband conversion loss of the mixer is 8.1dB@183GHz when the local oscillator signal is 4mw@91GHz. In the RF bandwidth from 173 GHz to 191 GHz, the single-sideband conversion loss is less than −10.6 dB. At the same time, the RF port return loss is less than 9.8 dB.

Development of a Wideband 220-GHz Subharmonic Mixer Based on GaAs Monolithic Integration Technology

A wideband 220 GHz subharmonic mixer based on monolithic integration technology is proposed in this paper. It features 12 Mm-thick GaAs membrane with anti-parallel Schottky diodes working at THz band monolithically integrated on the membrane. The optimization principles of low-parastics Schottky diodes and the fabrication process of GaAs MMIC membrane diodes are elaborated. To realize optimum performances of the mixer, the dimensions of the integrated diodes and the matching network are optimized with harmonic balance simulation and load-pull techniques. An IF low pass filter with compact microstrip resonance cell (CMRC) configuration and an improved perpendicular coax-to-microstrip connection are used to realize wide IF band. The measured results show that the single sideband (SSB) conversion loss of this mixer is less than 10.5 dB from 185 to 255 GHz with fixed IF of 1 GHz, while the double sideband (DSB) noise temperature is better than 1400 K in this frequency range. Using fixed local oscillator (LO) frequency of 110 GHz, the measured SSB conversion loss is 7.4-10.7 dB within 185-255 GHz, indicating the good performances of the mixer with IF from DC to 35 GHz. The GaAs monolithic integration technology provides an approach for massive manufacturing of identical circuits and the proposed mixer with wideband characteristics will be applied in 220 GHz imaging systems in the near future.

Frequency Multiplier and Mixer MMICs Based on a Metamorphic HEMT Technology Including Schottky Diodes

This paper reports on the monolithic integration of layout-optimized Schottky diodes realized in an established 50-nm gate-length metamorphic high-electron-mobility transistor technology for use in multifunctional nonlinear circuits. The suitability of the realized Schottky diodes is demonstrated by a broadband millimeter-wave I/Q-mixer (In-phase/Quadrature) and local oscillator (LO) chain comprising two power amplifiers and a frequency tripler, fabricated on monolithic microwave integrated circuits (MMICs). Both circuits are based on an anti-parallel Schottky diode topology. The subharmonically-pumped I/Q-mixer covers an RF (radio frequency) and IF (intermediate frequency) range of at least 75 GHz to 110 GHz and 0.5 GHz to 15 GHz, respectively. The single-sideband conversion loss is between 14 dB and 16 dB across most of the entire RF and IF bands. The core of the LO chain consists of a frequency tripler (multiplier by three) and features a bias-adjustable output power with almost constant conversion efficiency and a control range of more than 8 dB. The fully-integrated LO chain MMIC matches the needs of the presented I/Q-mixer and exhibits an average output power of 16.3 dBm with a covered frequency range of 38 GHz to 60 GHz. The unwanted harmonics are suppressed by at least -25.9 dBc below the third harmonic for the entire frequency range and better than -32.1 dBc for most part of the band. Thus, the mixer and tripler MMICs demonstrate state-of-the-art performance with regards to, e.g., covered bandwidth, output power, harmonic suppression, or 1 dB compression point.

A G-Band 2-Pixel Heterodyne Receiver with Integrated Local Oscillator Chain

A 2-pixel heterodyne receiver working in the 173–205-GHz band is presented in this paper. This receiver prototype is mainly composed of two balanced Schottky-based quadrature mixers and an integrated local oscillator (LO) chain. Based on sub-harmonically pumped mixing and quadrature coupling schemes, the proposed receiver operates in double sideband (DSB) mode or single sideband (SSB) mode. With combination of an external intermediate frequency (IF) 3-dB quadrature hybrid, the receiver can furtherly operate in sideband separation (2SB) mode. E-plane Riblet short-slot couplers combined with probe transitions are firstly employed in the radio frequency (RF) and LO path to realize quadrature configuration simultaneously; detailed theoretical derivation on 2SB operation is also given. The 2-pixel receiver is fabricated and tested, the measured SSB conversion loss of each channel achieves 12–20 dB when pumped with 18 dBm of input power at Ku-band, and the imbalance of conversion loss is less than 2 dB between all the IF ports. The typical sideband rejection ratio (SRR) is 12–16 dB over the operation frequency band. The corresponding achievements are valuable in the follow-up focal plane array detection system.

A 290–310 GHz Single Sideband Mixer With Integrated Waveguide Filters

A 290–310 GHz Schottky diode based subharmonic mixer with integrated, low loss, impedance matching waveguide cavity filters is presented in this paper. This mixer was designed for use in a 300 GHz communication system with a 20 GHz intermediate frequency band centred at 15 GHz. Image rejection of the 260–280 GHz lower sideband, as well as impedance matching, was achieved using an integrated third-order filter in the RF waveguide. The conventional coupling matrix was used to design the filter even though the impedance presented to the RF port was complex and frequency dependent. The mixer was measured to have: 1) single sideband conversion loss of 9–10 dB across the upper sideband, with a mixer noise temperature of 2000–2600 K; 2) a return loss at the RF port better than 12 dB, with three filter reflection zeroes (poles) distinguishable; and 3) a sideband rejection ratio from 13 to 25 dB, demonstrating the RF filter's excellent performance in terms of impedance matching and filtering.

A 220 GHz subharmonic mixer based on schottky diodes with an accurate terahertz diode model

ABSTRACTThis article introduces the design process of a 220 GHz subharmonic mixer with low conversion loss, which is comprised of a pair of anti‐parallel Schottky diodes (SBD). For terahertz circuits, the wavelength of the electromagnetic (EM) wave is very close to the size of devices, which results in complicated parasitic effects. This will leads to a very limited optimization space for circuits design when matching the impedance. To solve this problem, we developed the precise 3D EM planar SBD model and the field‐circuit co‐simulation method to design this terahertz mixer. The diodes are mounted on the quartz‐based suspended microstrip line. The measured results show that the single side band conversion loss is less than 12 dB during radio frequency (RF) range from 211 to 226 GHz and the minimum loss is about 5.9 dB. With the intermediate frequency fixed at 1 GHz, the conversion loss varies from 8 dB to 11.2 dB over the RF bandwidth of 211 to 221 GHz. The mixer can be applied in heterodyne receivers of terahertz systems. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2311–2316, 2016

273-GHz 2X Subharmonic Up-Conversion Mixer for System-on-Package Applications

In this paper, a 273-GHz 2X subharmonic passive mixer is proposed for system-on-package applications. The mixer is designed and implemented using thin-film microstrip line on a three-layer package platform. The antiparallel-diode-pair-based mixer up-converts the 135-GHz IF input signal to 273 GHz with a 69-GHz local oscillator. The isolation between the IF and RF ports is achieved by a duplexer. The duplexer is composed of two dual-mode bandpass filters with uniform/nonuniform square ring resonators. The mixer is fabricated and measured, and the measured single-sideband conversion loss is 17.7 dB with an output RF of 270 GHz.

A V-band quasi-optical GaAs HEMT monolithic integrated antenna and receiver front end

A single-chip monolithic integrated V-band folded-slot antenna with two Schottky-barrier diodes and a local oscillator source is developed as a quasi-optical receiver for the first time. The monolithic microwave integrated circuit consists of a voltage-controlled oscillator (VCO), a coplanar waveguide (CPW)-to-slotline transition, a low-pass filter, a folded-slot antenna, and a 180/spl deg/ single balanced mixer. The chip is fabricated based on the 0.15-/spl mu/m GaAs high electron-mobility transistor technology and the overall chip size is 3/spl times/1.5 mm/sup 2/. A finite-difference time-domain method solver is also developed for analyzing the embedded impedance characteristics of the folded-slot antenna to design the mixer. The chip is placed on an extended hemispherical silicon substrate lens to be a quasi-optical receiver. The performance of the receiver is verified by experimental measurements. The VCO has achieved a tuning range from 61.9 to 62.5 GHz and approximately 9.3-dBm output power. The CPW-to-slotline transition has bandwidth from 50 to 70 GHz. The mixer results in 15-dB single-sideband conversion loss and the receiving patterns of the IF power are also measured.

MOVPE-grown millimeter-wave InGaAs mixer diode technology and characteristics

The merits of InGaAs-based millimeter-wave mixer diodes are explored experimentally and theoretically. Schottky junctions on InGaAs exhibit barriers (/spl phi//sub b/) in the neighborhood of 0.25 eV. The high mobility of InGaAs contributes to the low n/sup +/ sheet resistances of 1.9-5 /spl Omega//square for 1-/spl mu/m n/sup +/ InGaAs layers (n/sub s/=1.5/spl times/10/sup 19/ cm/sup -3/, /spl mu//sub n/=1800 cm/sup 2//V/spl middot/s) grown with our in-house Metalorganic Vapor Phase Epitaxy (MOVPE) system, The design, material growth, fabrication, and characterization of InGaAs integrated mixer/antennae are reported. Pt plating technology, adapted here for InGaAs Schottky contacts, has improved the ideality factor (/spl eta/) and yield relative to conventional evaporated Pt. With 810 /spl mu/W of local oscillator power, applied to the diode, and zero DC bias, an integrated InGaAs mixer/antenna demonstrated an excellent diode performance of 199 K RF input double-sideband noise temperature with a corresponding single-sideband (SSB) conversion loss (L/sub c/) of 5.0 dB at LO, RF, and IF frequencies of 94 GHz, 94 GHz/spl plusmn/1.4 GHz, and 1.4 GHz, respectively. Likewise, the diodes in an InGaAs subharmonic integrated mixer/antenna demonstrated an equivalent RF-port double-sideband (DSB) noise temperature (T/sub mix/) of 1058 K and single-sideband conversion loss of 10.2 dB at 180 GHz with a 90-GHz LO power (PLO) of 1.6 mW. Compared to GaAs diodes with RF coupling and IF losses removed, the single-ended InGaAs noise temperature results were within 46-100 K of those for state-of-the-art GaAs mixer diodes while requiring significantly less LO power.

Otpically illuminated dielectric interfaces as high-speed far-infrared modulators

A new device for the gigahertz modulation of far-infrared radiation is analytically and numerically analyzed. It consists of a thin layer of a high-mobility, direct-bandgap semiconductor, such as GaAs, in which a high-density electron-hole plasma is rapidly created and destroyed, thereby rapidly changing the free-carrier reflectivity of the active layer. Illumination by a high-power, near-infrared laser diode array generates the plasma through intrinsic photoconduction. It is shown that this device acis primarily as an amplitude modulator, and that its efficiency increases sharply with increasing far-IR frequency, in contrast to a Schottky diode, which acts primarily as a phase modulator, and whose efficiency falls off sharply with far-IR frequency. The breakeven frequency lies at about 1.5 THz, depending slightly on the assumed device parameters. The relative advantage of the new device increases rapidly with increasing far-infrared frequency. At an operating frequency of 2.5 THz (119 μm), for example, a 1 GHz modulation bandwidth may be achieved with a single-sideband conversion loss of only-21 db, versus a Schottky's loss of-39 db, assuming a laser diode power of 1 W, which is readily available from recently developed laser diode arrays.

Heterodyne mixing at 70 GHz with superconductor-insulator-superconductor tunnel junctions

A laboratory heterodyne receiver working at 70 GHz was built up using superconductor-insulator-superconductor tunnel junction as mixing element. Single sideband conversion loss LC as low as 1.92±0.23 and mixer noise temperature TM of less than 100 K have been achieved while local oscillator pump power is 4·10−8W.

Low noise single-ended mixer for 230 GHz

Performance of a single-ended fundamental frequency diode mixer, designed for cooled operation in the frequency range 190–260 GHz, is reported. At 230 GHz the best single sideband (SSB) mixer temperature obtained was 300 K, when the mixer was cooled to 20 K, with a corresponding SSB conversion loss of 5.9 dB. The significant improvement compared to previously reported results is attributed to the novel mixer mount design and to the optimum empirical choice of diode electrical parameters.