Waveguide Packaging Research Articles

Silicon Micromachined Waveguide Circuit for a 2 THz Schottky Receiver: Progress and Challenges

Space instruments that operate in the THz range can enable unique measurements for a better understanding of the chemical and physical processes taking place in our Universe. One such application of this technology is a compact 2.06 THz receiver that can measure the ionized oxygen line to determine wind velocity in Earth's upper atmosphere. Metal machined waveguide circuits have long been utilized to build and demonstrate functional receivers in the submillimeter-wave range. However, as the operational frequency is increased, extremely challenging requirements are placed on metal machining in terms of the required precision, surface roughness, and alignment tolerance. This work describes the design and implementation of the first-of-its-kind, vertically-integrated, 2-THz Schottky diode mixer using precise silicon micromachine technology. A traditional e-plane split waveguide package is re-designed to utilize the three-dimensional (3-D) capability of stacking silicon micromachined parts. The silicon microfabrication process has been optimized to produce smooth and precise features for packaging a 2 THz subharmonic GaAs Schottky diode mixer, providing surface roughness better than 1-micron rms with less than 5% variation on critical dimensions. The subharmonic mixer and a fully solid-state local oscillator (LO) chain is currently being implemented to validate silicon micromachining for THz packaging. The impact of micromachining variation on mixer performance is explored through simulations over a range of dimensions on the most sensitive regions of the Si module.

WR-3.4 Overmoded Waveguide Module for the Packaging of a Linear Integrated-Circuit Array

The performance of WR-3.4 overmoded waveguide modules containing a linear array of discrete terahertz integrated circuits is presented to verify a new power-combining technique. Custom-designed thru-line IC chips that include back-to-back broadband antenna transitions were fabricated with an area of 390 × 750 mm2 for waveguide packaging. Multiple array modules were assembled to verify the repeatability in performance. The array modules exhibited almost identical amounts of insertion losses compared with single-element modules, showing the best insertion loss of 2.6 dB over a 1 dB bandwidth of 95 GHz.

E-band transceiver monolithic microwave integrated circuit in a waveguide package for millimeter-wave radio channel emulation applications

E-band transceiver monolithic microwave integrated circuit in a waveguide package for millimeter-wave radio channel emulation applications

A Sub-6G SP32T Single-Chip Switch with Nanosecond Switching Speed for 5G Applications in 0.25 μm GaAs Technology

This paper presents a single-pole 32-throw (SP32T) switch with an operating frequency of up to 6 GHz for 5G communication applications. Compared to the traditional SP32T module implemented by the waveguide package with large volume and power, the proposed switch can significantly simplify the system with a smaller size and light weight. The proposed SP32T scheme utilizing tree structure can dramatically reduce the dc power and enhance isolation between different output ports, which makes it suitable for low-power 5G communication. A design methodology of a novel transmission (ABCD) matrix is proposed to optimize the switch, which can achieve low insertion loss and high isolation simultaneously. The average insertion loss and the isolations are 1.5 and 35 dB at 6 GHz operating frequency, respectively. The switch exhibits the measured input return loss which is better than 10 dB at 6 GHz. The 1 dB input compression point of SP32T is 15 dBm. The prototype is designed in 5 V 0.25 μm GaAs technology and occupies a small area of 12 mm2.

77/79-GHz Forward-Wave Directional Coupler Component Based on Microstrip and SIW for FMCW Radar Application

A low-cost 77/79-GHz ladder-type forward-wave directional coupler (FWDC) is proposed based on microstrip and substrate integrated waveguide (SIW) for frequency modulated continuous wave (FMCW) radar application in this article. The SIW structures are periodically loaded between two parallel microstrip lines. In the circuit topology of the proposed FWDC, the impedance matching between the even/odd modes is achieved. Meanwhile, an approximate constant phase difference (about 12°) between the even and odd modes is designed within 76–81 GHz. The proposed FWDC is modeled by the Bloch–Floquet theorem, and the design procedure is given. Besides, the full-microstrip ladder-type FWDC is discussed and its theoretical analysis demonstrates that such an FWDC with a weak coupling cannot be obtained using the full-microstrip topology. Finally, the proposed FWDC is fabricated by the PCB technology. To measure its performances, $W$ -band fin-line microstrip-waveguide transition and waveguide package are utilized, and three waveguide packaging cases are measured and discussed. Good agreement between the simulations and measurements is achieved.

Design of Broadband W-Band Waveguide Package and Application to Low Noise Amplifier Module

In this paper, the broadband millimeter-wave waveguide package, which can cover the entire W-band (75–110 GHz) is presented and applied to build a low noise amplifier module. For this purpose, a broadband waveguide-to-microstrip transition was designed using an extended E-plane probe in a low-loss and thin dielectric substrate. The end of the probe substrate was firmly fixed on to the waveguide wall in order to minimize the performance degradation caused by the probable bending of the substrate. In addition, we predicted and analyzed in-band resonances by the simulations that are caused by the empty spaces in the waveguide package to accommodate integrated circuits (ICs) and external bias circuits. These resonances are removed by designing an asymmetrical bias space structure with a radiation boundary at an external bias connection plane. The bond-wires, which are used to connect the ICs with the transition, can generate impedance mismatches and limit the bandwidth performance of the waveguide package. Their effect is carefully compensated for by designing the broadband two-section matching circuits in the transition substrate. Finally, the broadband waveguide package is designed using a commercial three-dimensional electromagnetic structure simulator and applied to build a W-band low noise amplifier module. The measurement of the back-to-back connected waveguide-to-microstrip transition including the empty spaces for the ICs and bias circuits showed the insertion loss less than 3.5 dB and return loss higher than 13.3 dB across the entire W-band without any in-band resonances. The measured insertion loss includes the losses of 8.7 mm-long microstrip line and 41.8 mm-long waveguide section. The designed waveguide package was utilized to build the low noise amplifier module that had a measured gain greater than 14.9 dB from 75 GHz to 105 GHz (>12.9 dB at the entire W-band) and noise figure less than 4.4 dB from 93.5 GHz to 94.5 GHz.

Design and Research on a Biped Clamp and Pull Piezoelectric Linear Motor Based on Inchworm Principle

The piezoelectric linear motor based on piezoelectric ceramic stack has a potential in high-tech field’s application such as optical waveguide packaging. Mechanical properties of piezoelectric linear motors in the existing researches still need to be improved. So have designed double foot clamping type piezoelectric linear motor based on the principle of inchworm, and analyzed the working principle. The performance analysis of the driving mechanism shows that the relationship between the amplitude of driving mechanism and voltage values is positively proportional, and the influence of frequency on its amplitude is not big. The performance of the clamping mechanism was studied through experiments. First, verified the feasibility of the principle, tested the amplitude and found that the amplitude increases with the increase of the voltage, but due to the influence of clamping mechanism modal, amplitude tends to be zero as frequency increase to a certain extent. Second, amplitudes of the driving foot in two clamping mechanism were compared to ensure the consistency of amplitude of each driving foot, and the magnification of driving mechanism displacement was obtained by clamping mechanism in the practical work. Analyzed the rail vibration caused by driving foot and the prototype speed characteristics and load characteristic, and obtained speed characteristic curve are, in which, the speed of the motor increases with increasing voltage, but will not be able to continue to increase when the voltage reached to 60V, and the related curve between frequency and speed is similar to the frequency characteristic curve of the clamping mechanism, which is mainly due to the impact from the clamping mechanism modal. Obtained the maximum output of the motor power is 1.8 N through the load characteristic experiment.

Uniform-Field Over-Mode Waveguide for Spatial Power-Combining Applications

A new and effective millimeter-wave waveguide packaging technique suitable for 1-D spatial power-combining applications is presented. The transition structure using narrow corporate channels preserves the uniform field distribution when expanding the ${E}$ -plane width of a standard waveguide to several wavelengths. A Q-band test module, containing back-to-back transitions for an increased width from 2.84 to 52 mm, shows an average insertion loss of 0.34 dB in the 40–50-GHz range. The radiation patterns from an open-end module, cut in half from the original test module, confirm uniform field distribution across the over-mode guide aperture.

Gap Waveguide PMC Packaging for Two-Layer PEC Surfaces

This paper shows the investigation of gap waveguide (GW) packaging for an irregular perfect electric conductor (PEC) composed of two layers of metal surfaces. The stopband for a GW with two-layer PEC surfaces is carefully studied, considering the top-layer PEC width, pin size, pin height, columns of pins, as well as dielectric substrate thickness and permittivity. A strategy of the GW packaging for such an irregular PEC surface is presented. In addition to the unit cell-based stopband study, such GW packaging is also demonstrated for a substrate-integrated waveguide (SIW)–microstrip line structure, which is typical of the circuit with two-layer PEC surfaces. A Chebychev bandpass filter built on the SIW and microstrip line is finally designed and fabricated to provide experimental verifications. In particular, a dedicated defect of the side air gap existing in the SIW-based circuits using the GW PMC packaging is found, and an effective remedy is presented.

Sub-Millimeter and Terahertz-Wave Packaging for Large Chip-Width MMICs

We present novel waveguide packaging for sub-millimeter and terahertz-wave devices, which is suitable for large chip-width MMICs and doesn't require any additional fabrication process. With full electromagnetic simulation, we analyze possible wave modes in a rectangular waveguide with thin E-plane slits formed for inserting large-width MMICs into the split waveguide block and show that parasitic modes can be well suppressed by lossy and high-dielectric material. For a 1.1-mm-wide test IC in the 260–320 GHz band, measured transition loss is around 1 dB with more than 60 dB inter-port isolation.

A Submillimeter Wave InP HEMT Multiplier Chain

In this letter, we demonstrate the first 400 GHz multiplier chain with integrated buffer amplifiers through the chain. The x9 multiplier chain uses 25 nm InP HEMT MMIC technology. The chain consists of three packaged MMICs in split-block waveguide packages with each multiplier incorporating an integrated output buffer. We report a peak output of 6.9 mW and greater than 4 mW over a 10% bandwidth.

Fuzzy multi-objective optimization for movement performance of deep-notch elliptical flexure hinges.

Compared with commonly used flexure hinges, deep-notch elliptical flexure hinges are more suitable for flexible mechanisms with high precise transmission requirements. The rotation stiffness model of deep-notch elliptical flexure hinges was built first, and the compliance matrix was analyzed and solved by using Newton-Cotes quadrature formula to simplify the calculation of compliance coefficients; on the other hand, the fuzzy multi-objective optimization model with distribution was constructed, and a detailed example was given out to validate the effectiveness of the fuzzy optimization. The experiment results show that the desired angular displacement α(z) around the z axis is increased by 30.13%; while the undesired α(y) that around the y axis is decreased by 15.74% in experiment. The line displacements of Δ(y) and Δ(z) along the Y and Z axes are decreased by 18.15% and 47.69%, respectively. All the optimization data show that after the fuzzy optimization, the rotation capacity of z axis has been raised, and the motion capacity of the undesired directions has been restrained, so that the movement precision and the performance of the deep-notch elliptical flexure hinge can be improved, which is more suitable for the optical waveguide packaging positioning platform with high precision transmission.

MHEMT $G$-Band Low-Noise Amplifiers

To improve the performance of G-band equipment for humidity sounding of the atmosphere, a high-gain and low-noise amplifier is needed. Here, the performances of 165 and 183 GHz low-noise amplifier microchips intended for atmospheric water vapor profiling application are reported. The microchips are manufactured in metamorphic high-electron mobility transistor technology having a gate length of 50 nm. The on-wafer measured results show noise figures of 4.4-7.4 dB and 16-25 dB gain at the operating frequencies. In addition, two of the amplifiers were assembled in waveguide packages and the measured results show a gain of 19-20 dB and 7 dB noise figure at both 165 and 183 GHz.

Gap Waveguide PMC Packaging for Improved Isolation of Circuit Components in High-Frequency Microwave Modules

In this paper, perfect magnetic conductor (PMC)-based packaging technique was used to improve the isolation performance among various microwave circuit components such as high-gain amplifier chains. In this approach, a periodic structure (such as metal pin rows) together with the ground plane of the substrate created a stopband for unwanted parallel plate or cavity modes as well as substrate modes, and thereby suppressed the problems of circuit resonances and related package phenomena. This paper describes two Ka-band amplifier chains that were tested with this new packaging technique. Firstly, a single amplifier chain was tested for maximum stable gain operation, and it was found that the stable gain of was achieved, whereas traditional metal wall package with RF absorber offered stable gain of 40 dB, thus showing significant isolation improvement. Secondly, two high-gain amplifier chains were placed side by side and their mutual isolation was tested. With the proposed gap waveguide packaging, a minimum isolation of 78 dB was achieved, whereas a complete metal shield provided a minimum isolation of only 64 dB over the band of interest.

Approximation of Coupling Mode and Fitting Alignment in Planar Light Waveguide Packaging

This paper describes a new active optical alignment method that is developed for the alignment of optical fibers to planar waveguide in order to improve the precision and efficiency of that. A new coupling mode, which is a polynomial function, is rebuilt by simplifying effect factors of the light field coupling process, such as angular offsets and line offsets. The optimum curve which is calculated to fit those sampling points by taking advantage of the least square method assists to locate the maximum coupling point of the alignment. Simulation results show that the alignment of two single mode fields is improved into 0.1μm precision with only 6 sampling points by the new method instead of 0.4μm offset with average 21.4 sample points by hill-climbing method. Using this alignment method, a fiber-to-waveguide, high-efficient coupling that provides higher accurate alignment with less sampling points is achieved.

Optical Properties of the Coupling Interface for Planar Optical Waveguides

Planar optical waveguides are the key elements in a modern, high-speed optical network. An important problem facing the optical fiber communication system, specifically planar optical waveguides, is coupling. The current study presents a coupling model for planar optical waveguides and optical fibers. The various effects of the optical properties of the coupling interface were analyzed by the scalar finite difference beam propagation method, including the thickness, with or without the matching refractive index of the interface adhesive. The findings can serve as a guide for planar optical waveguide packaging.

Quality Standardization for Polydimethysiloxane-Based Optical Interconnect Production From Optical Aspects

The influences of waveguide materials, fabrication conditions, and packaging substrates on the optical waveguide properties of electrical-optical circuit boards have been investigated by systematic variation of these conditions. Pt catalyst in polydimethysiloxane, casting mould sidewall roughness, interlay thickness, and packaging substrates show sensitive impact on optical waveguide insertion loss and in terms of defined target of optical loss, the basic quality criteria can be defined before production.

Effects of Adhesive on Coupling Efficiency of Planar Light Waveguide Packaging

Problem statement: Advanced optoelectronic devices are a kind of key and basic components for next generation communication, untouched sensor, medical testing. They have lots of advantages including greater communication performance, larger capacity, and more fixable form. But light coupling and package structure seriously affects performance of optoelectronic devices. So a lot of attaching methods were proposed to package optoelectronic devices. A popular method which was widely used is a UV epoxy adhesive which can solidify the coupling interface with high mechanical strength and submicron displacement. In order to obtain high coupling efficiency, coupling approximation after adhesive is needed. Approach: In this study, firstly, the light coupling model was introduced. Then light beam propagation mode after adhesive with the same refractive index as that of light path was presented and the function modeling of couple model was derived. Finally, a slanted-plane structure of interface was considered and coupling approximation after adhesive was calculated. Results: Simulations and experimental results indicate that theoretical coupling efficiency and measured coupling efficiency agree with very well and the couple loss decrease about 0.4dB after adhesive. Conclusion: The matching adhesive could obviously increase the coupling efficiency and the approximation function could realize to predict the variation of coupling efficiency before or after adhesive accurately.

A thermocompressive bonding method using a pure sputtered Au layer and its wafer scale package application

The authors have developed a thermocompressive bonding method using a sputtered Au layer and applied it to the coplanar waveguide (CPW) package. The bonding temperature is 350°C, the bonding pressure is 63MPa, and the duration time is limited to 30min. The bonding strength is evaluated using the Scotch tape and tweezers detaching method and the hermeticity is evaluated using helium leak detection work station. The measured hermeticity is 1.0×10−9Pam3∕s. To measure the electrical properties, the CPW line is packaged and the rf characteristics and dc resistance are measured. The insertion loss of the packaged CPW line is −0.074dB at 2GHz and the dc resistance is from 0.019to0.046Ω. This result shows that their Au compressive bonding method is very useful and good for microdevice wafer level packaging applications.

A Novel Micromachined Frequency Tripler Hybrid Component for Integrated Millimeter Wave Subsystems

A fully integrated broadband distributed frequency tripler, periodically loaded with HBV devices, has been designed and fabricated and has demonstrated the generation of a broad range of output frequencies of up to 570 GHz. Key to the design is the principle that the entire frequency tripler circuit is produced monolithically and incorporates novel HBV devices electrically and mechanically interconnected by a thin low-loss SU-8 membrane. With the device fabrication approach used, the novel HBV devices are able to produce a higher capacitance-voltage swing ratio whilst simultaneously minimizing the device series and contact resistances to achieve the optimum conversion efficiency. The entire concept of this work was to design a cost effective fully integrated waveguide package, with the frequency tripler circuit mounted at the E-plane of a micromachined waveguide which was constructed with stepped height and width to prevent the propagation of higher order modes inside the waveguide sections. The micromachined waveguide sections exhibit high dimensional accuracy and a good surface finish which is necessary for the efficient propagation of high frequency signals. The frequency tripler circuit and the accompanying micromachined waveguide sections are mounted in a specifically designed metal test fixture to form a compact and cost-effective subcomponent with great commercial potential for broadband harmonic generation of up to terahertz frequencies. This paper presents the design methodology and techniques used to produce the frequency tripler package, together with some initial measurement results.