In this study, a metamaterial-based LTCC compressed Luneburg lens was designed, manufactured and measured. The lens was designed at 60 GHz to utilize the unlicensed mm-wave spectrum available for ...short-range high-capacity wireless communication networks. The transformation optics method was applied to ensure the compression of the Luneburg lens antenna and thus maintain a low-profile structure. The two different types of unit cells for low and high permittivity regions were considered. The parametric study of the effect of compression on lens performance was presented. The antenna is implemented with a standard high-permittivity LTCC process, and details of the manufacturing process for the metamaterial lens are discussed. The low-profile lens is thinner than 2 mm and measures 19 mm in diameter. A size reduction of 63.6% in comparison with a spherical lens was achieved. The near-field to far-field mm-wave measurement technique is presented, and the measurement results show a peak antenna gain of 16 dBi at 60 GHz and a beam-scanning capacity with 1 dB scan loss within a 50° field of view.
The creation of hole, cavity or channel structures in low-temperature cofired ceramics (LTCCs), using different sacrificial volume materials (SVMs) was tested. The main functionality of the SVMs ...should be: easy application into the holes; protection of holes during lamination; uninhibited lamination between layers; and, during firing should burn out before the pores of the LTCCs close, to leave the empty holes clear of any residue. Five different materials were tested—hydroxyethyl cellulose (HEC) 2 wt%, HEC 5 wt%, agar-agar, gelatin, and commercial carbon paste—and compared to a reference sample where no SVMs were used. In all cases, lamination parameters were minimised in order to preserve the tested hole structures. Matrixes with holes ranging from 158 to 268 µm, with pitches of 573 µm in a green state, were tested. The agar-agar caused ceramic deformation as a result of thermal burst during firing and the lamination between the layers was compromised. The carbon paste was difficult to handle, requiring extra equipment for hole filling and incomplete filling of the larger holes. Traces of carbon paste were left as a landing pad on top of the holes, inhibiting lamination at these areas. The gelatin and the 2 wt% and 5 wt% hydroxyethylcellulose (HEC 2 wt% and HEC 5 wt%) filled all holes completely, and also worked as adhesive-assisted lamination (AAL) materials with excellent lamination between layers. Excellent lamination was also observed in the no-SVM case. Thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) analyses established that, for all SVMs tested, the remaining residue is negligible after firing. As a result, the HEC 2 wt% material was considered ideal for use as an SVM.
A 60-GHz active microstrip antenna design comprising a three-stage pseudomorphic high electron mobility transistor amplifier integrated with a high gain antenna on an alumina substrate is presented. ...The amplifier has 18-dB gain and is ribbon bonded to the substrate on which the antenna is defined. The antenna is a microstrip array antenna with a simple etched pattern for producibility at high frequencies. Two antenna layouts are designed, for different coverage areas: a single array having 13.4-dBi directivity and a double array with 14.6-dBi directivity. Antenna losses are approximately 1-2 dB, giving antenna gains of about 12 and 13 dBi, respectively. Mechanical simplicity is achieved with this design, and unnecessary transitions are avoided. Measurements are performed on amplifier and antenna separately, as well as on the integrated design. Amplifier chips with and without benzocyclobutene passivation are fabricated and measured for comparison
Two single-chip frequency multiplier chains targeting 118 and 183 GHz output frequencies are presented. The chips are fabricated in a 0.1 ¿m GaAs metamorphic high electron-mobility transistor ...process. The D-band frequency doubler chain covers 110 to 130 GHz with peak output power of 5 dBm. The chip requires 2 dBm input power and consumes only 65 mW of dc power. The signal at the fundamental frequency is suppressed more than 25 dB compared to the desired output signal over the band of interest. The G-band frequency sextupler (×6) chain covers 155 to 195 GHz with 0 dBm peak output power and requires 6.5 dBm input power and 92.5 mW dc power. The input signal to the multiplier chain can be reduced to 4 dBm while the output power drops only by 0.5 dB. The unwanted harmonics are suppressed more than 30 dB compared to the desired signal. An additional 183 GHz power amplifier is presented to be used after the ×6 frequency multiplier chain if higher output power is required. The amplifier delivers 5 dBm output power with a small-signal gain of 9 dB from 155 to 195 GHz. The impedance matching networks are realized using coupled transmission lines which is shown to be a scalable and straightforward structure to use in amplifier design. Microstrip transmission lines are used in all the designs.
A grid array antenna working around 145 GHz is proposed in this paper. The antenna is built on liquid crystal polymer (LCP) and designed for the D-band antenna-in-package application. The intrinsic ...softness of the LCP material is a limiting factor of the antenna's aperture size. A 0.5-mm-thick copper core is used to compensate. By doing this, the rigidness of the antenna is effectively improved, compared with an antenna without the copper core. Wet etching is used to realize the patterns on the top and bottom conductor. Compared with a low-temperature cofired ceramic counterpart, we obtain a considerable cost reduction with acceptable performance. The proposed antenna has an impedance bandwidth of 136-157 GHz, a maximum gain of 14.5 dBi at 146 GHz, and vertical beams in the broadside direction between 141 and 149 GHz. The fabrication procedures of the antennas are introduced, and a parametric study is carried out, which shows the antenna's robustness against fabrication tolerances, such as the not-well-controlled etching rate and the substrate surface roughness. This makes the antenna a promising solution for mass production.
Single-chip 60 GHz transmitter (TX) and receiver (RX) MMICs have been designed and characterized in a 0.15mum (f T ~ 120 GHz/f MAX > 200 GHz) GaAs mHEMT MMIC process. This paper describes the second ...generation of single-chip TX and RX MMICs together with work on packaging (e.g., flip-chip) and system measurements. Compared to the first generation of the designs in a commercial pHEMT technology, the MMICs presented in this paper show the same high level of integration but occupy smaller chip area and have higher gain and output power at only half the DC power consumption. The system operates with a LO signal in the range of 7-8 GHz. This LO signal is multiplied in an integrated multiply-by-eight (X8) LO multiplier chain, resulting in an IF center frequency of 2.5 GHz. Packaging and interconnects are discussed and as an alternative to wire bonding, flip-chip assembly tests are presented and discussed. System measurements are also described where bit error rate (BER) and eye diagrams are measured when the presented TX and RX MMICs transmits and receives a modulated signal. A data rate of 1.5 Gb/s with simple ASK modulation was achieved, restricted by the measurement setup rather than the TX and RX MMICs. These tests indicate that the presented MMICs are especially well suited for transmission and reception of wireless signals at data rates of several Gb/s
This paper describes a camera-less eye-tracker using an instrumented contact lens fitted with photodetectors and illuminated by eyewear. The gaze direction is computed on the lens using the ...photo-currents by means of a mixed signal 0.35-\mum CMOS ASIC. NFC is used to power the ASIC and to transmit the gaze direction to the eyewear. Experimental measurements are performed using a prototype scleral contact lens mounted on a mock-up eye. The measurements show that an accuracy of 0.2^{\mathrm{\circ}} is achievable, i.e. 2.5 times better than current mobile video-based eye-trackers, for a power consumption of 170 \muW. Several tests were carried out on several ASICs, demonstrating system reliability despite process variations, operating time, and supply voltage variations.
This paper reports on a flip-chip (FC)-based multichip module (MCM) for low phase-noise (PN) V-band frequency generation. A high-performance ×8 GaAs metamorphic high-electron mobility transistor ...monolithic microwave integrated circuit (MMIC) multiplier and a low PN 7-GHz GaAs InGaP heterojunction bipolar transistor (HBT) MMIC oscillator were used in the module. The microstrip MMICs were FC bonded to an Al 2 O 3 carrier with patterns optimized for low-loss transitions. The FC-based module was experimentally characterized to have a PN of -88 dBc/Hz @ 100-kHz offset and -112 dBc/Hz @ 1-MHz offset with an output power of 11 dBm. For comparison, the MMICs were also FC bonded as individual chips and the performance was compared with the bare dies without FC bonding. It was verified that the FC bonding has no detrimental effect on the MMIC performance. The tests revealed that the FC module provided improved performance. To our best knowledge, this is the first FC-based module for millimeter-wave frequency generation. The module also presents one of the best PN reported for millimeter-wave frequency sources.
Parylene-C is a polymeric material primarily used in hybrid manufacturing for humidity protection and dielectric isolation. In this study, the influence of Parylene-C on passive millimeter-wave ...circuits such as transmission lines and resonators is investigated in electromagnetic simulations up to 100 GHz and measurements up to 67 GHz. It is demonstrated that when applying 5-mum Parylene-C, the resonance frequency of a resonator is shifted 0.4% and the Q value is changed slightly. The dissipation factor of the Parylene-C versus frequency has been calculated from measured data. The flip-chip mounted broadband traveling-wave monolithic-microwave integrated-circuit (MMIC) amplifier is also investigated. A 5-mum-thick Parylene-C coat results in a total loss of 1.04 dB. A positive side effect of the Parylene-C is that it allows heat, dissipated in the amplifier, to spread over a larger area, consequently lowering the backside temperature of the flipped MMIC with as much as 10 degC. The results from this study demonstrate that, concerning the electrical performance, Parylene-C is very well suited as protective coating in millimeter-wave applications and can be used as an alternative to a hermetic package in the frequency range from dc to 67 GHz to reduce weight and cost
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