Showing papers in "IEEE Microwave and Wireless Components Letters in 2011"
TL;DR: In this article, the authors demonstrate that the efficiency of wireless power transfer utilizing resonant coupling is improved by applying the "matching condition", which is achieved by varying the coupling factor between the source (load) and the internal resonator.
Abstract: We experimentally demonstrate that the efficiency of wireless power transfer utilizing resonant coupling is improved by applying the “matching condition.” The `matching condition' is extracted from an equivalent circuit model of a magnetically coupled wireless power transfer system. This condition is achieved by varying the coupling factor between the source (load) and the internal resonator. Applying this technique results in efficiency improvements of 46.2% and 29.3% at distances of 60 cm and 1 m, respectively. The maximum efficiency is 92.5% at 15 cm. A circuit model based on the extracted parameters of the resonators produces results similar to the experimental data.
228 citations
TL;DR: In this article, a microstrip diplexer with a joint T-shaped resonator was proposed for high isolation and wide stopband in addition to satisfying the passband requirement.
Abstract: This study presents a novel microstrip diplexer with a joint T-shaped resonator. The T-shaped resonator has an extremely small frequency ratio using microstrip with practical line width. Additionally, the T-shaped resonator can be used as a frequency selective signal splitter, making it feasible to design a diplexer for a system with two extremely close bands. The diplexer using a joint T-shaped resonator does not require combining circuits and matching networks. A diplexer used in the UMTS-WCDMA system is designed and measured. The proposed diplexer has high isolation and wide stopband in addition to satisfying the passband requirement. A satisfactory agreement between the simulated results and the measured results validate the proposed configuration.
147 citations
TL;DR: In this article, a miniaturized 3 dB branch-line hybrid coupler with second harmonic suppression using high-impedance transmission lines and interdigitated shunt capacitors is presented.
Abstract: This letter presents a miniaturized 3 dB branch-line hybrid coupler with second harmonic suppression using high-impedance transmission lines and interdigitated shunt capacitors. By using the interdigitated capacitors shunt with the transmission lines, further minimization of the 3 dB branch-line hybrid coupler can be achieved compared with previously reported techniques. The design of the interdigitated shunt capacitors requires concurrent optimization of the capacitance to the ground and the edge-coupling interdigitated capacitance between the ports. For validation, a miniaturized 3 dB branch-line hybrid coupler at 836.5 MHz was designed and implemented. The proposed 3 dB branch-line hybrid coupler achieved a compact size of 27.75 mm × 25.7 mm, or equivalently 0.077λo×0.072λo, where λo is the free-space wavelength. Moreover, the coupler can suppress second harmonic components by 20 dB while maintaining similar measured performance compared to the conventional branch-line hybrid coupler.
134 citations
TL;DR: In this article, a quad-band microstrip bandpass filter (BPF) using asymmetric stepped impedance resonators (SIRs) is proposed, which only employs two sets of the asymmetric SIRs.
Abstract: A new quad-band microstrip bandpass filter (BPF) using asymmetric stepped impedance resonators (SIRs) is proposed. The filter only employs two sets of the asymmetric SIRs. One set is designed to operate at the first and third passbands (2.4/5.2 GHz) and the other set is employed at second and fourth passbands (3.5/6.8 GHz). By tuning the impedance and length ratios of the asymmetric SIRs, a multi-band filter can be easily achieved. This study provides a simple and effective method to design a quad-band filter with low insertion loss and compact size. Experimental verification is provided and good agreement has been found between simulation and measurement.
132 citations
TL;DR: In this article, a novel application of shunt open-stubs at the feed points of a center fed coupled-line hairpin resonator is presented for the design of compact lowpass filter (LPF) with very wide stopband.
Abstract: A novel application of shunt open-stubs at the feed points of a center fed coupled-line hairpin resonator is presented for the design of compact lowpass filter (LPF) with very wide stopband. The transmission zeros of the basic unit are minimally affected by its association with the stubs. The stopband bandwidth and filter roll-off rates achieved here are larger than those achieved earlier. A prototype microstrip LPF having a very wide stopband up to nine times the filter cutoff frequency is fabricated.
128 citations
TL;DR: In this paper, the authors presented a novel ultra wideband (UWB) bandpass filter with a notched band using a ring resonator, and measured the 3 dB fractional bandwidths (FBWs) were 1028% and 1033% with and without the notched bands, respectively.
Abstract: This letter presents a novel ultra-wideband (UWB) bandpass filter (BPF) with a notched band using a ring resonator Bandwidths of the ring resonator with two stepped-impedance stubs are calculated by examining the relations between resonant frequencies and the characteristic impedance of the ring Stepped-impedance ports are used to obtain improved return losses in a high-frequency band Interdigital-coupled feed lines with an asymmetric structure embedded in the stepped-impedance ports are developed to avoid wireless local-area network (WLAN) signals at 5 GHz band Measured results show that 3 dB fractional bandwidths (FBWs) are 1028% and 1033% with and without the notched band, respectively Measured insertion loss of the notched band within the UWB is 1114 dB at 541 GHz
126 citations
TL;DR: In this article, a stub-loaded multiple-mode resonator (MMR) is constructed by loading three open stubs in a uniform-impedance resonator, i.e., one stepped-impingance stub at the center and two uniform-IMpedance stubs at the symmetrical side locations.
Abstract: Novel compact ultra-wideband (UWB) bandpass filter (BPF) using stub-loaded multiple-mode resonator (MMR) is presented in this letter. The MMR is constructed by loading three open stubs in a uniform-impedance resonator, i.e., one stepped-impedance stub at the center and two uniform-impedance stubs at the symmetrical side locations. Five modes, including two odd modes and three even modes, could be designed within UWB band, and two transmission zeros generated by the stepped-impedance stub improve the passband selectivity greatly. The letter shows modal resonant frequencies against the step-impedance-stub-loaded parameters, which can control the even modes flexibly, while the odd modes remain the same. A compact planar UWB BPF is simulated, fabricated and measured. The simulated and measured results are in good agreement and show good in-band filtering performance and sharp selectivity.
121 citations
TL;DR: In this article, a simple microstrip ring-resonator is presented for novel design of dual-band dual-mode bandpass filters with good isolation and upper-stopband performance.
Abstract: A simple microstrip ring-resonator is presented for novel design of dual-band dual-mode bandpass filters with good isolation and upper-stopband performance. By increasing the length of the loaded open-circuited stub, the two first-order degenerate modes are excited and slit for the use of the first passband, while one of the third-order degenerate modes moves downward and forms the second passband together with a second-order degenerate mode. Meanwhile, three transmission zeros are properly tuned for the rejections between the two passbands and in the upper stopband. After installing two coupled-line sections on a square ring at the two ports with 90°-separation, a dual-band filter with the two transmission poles in each passband is designed and measured. Without adding any additional perturbation element inside the ring, the measured filter shows good performance for both in-band matching and outside rejections of the desired dual passbands.
114 citations
TL;DR: A low-cost, fully-integrated antenna-in-package solution for 60 GHz phased-array systems is demonstrated, achieving excellent model-to-hardware correlation and beam-steered, non-line-of-sight links with data rates up to 5.3 Gb/s.
Abstract: A low-cost, fully-integrated antenna-in-package solution for 60 GHz phased-array systems is demonstrated. Sixteen patch antennas are integrated into a 28 mm × 28 mm ball grid array together with a flip-chip attached transmitter or receiver IC. The packages have been implemented using low temperature co-fired ceramic technology. 60 GHz interconnects, including flip-chip transitions and via structures, are optimized using full-wave simulation. Anechoic chamber measurement has shown ~ 5 dBi unit antenna gain across all four IEEE 802.15.3c channels, achieving excellent model-to-hardware correlation. The packaged transmitter and receiver ICs, mounted on evaluation boards, have demonstrated beam-steered, non-line-of-sight links with data rates up to 5.3 Gb/s.
113 citations
TL;DR: In this article, a planar diplexer based on the substrate integrated waveguide (SIW) with complementary split-ring resonators (CSRRs) etched on the waveguide surface is developed.
Abstract: A novel high-performance planar diplexer is developed based on the substrate integrated waveguide (SIW) with complementary split-ring resonators (CSRRs) etched on the waveguide surface. The proposed diplexer is operated below the characteristic cutoff frequency of the waveguide. The filtering response of the SIW-CSRR combined structure is investigated first. The diplexer is then implemented based on two cascaded two-pole bandpass filters. Equivalent circuit, simulated results and experimental verification are all provided. This diplexer shows advantages in terms of the compact size, low loss, high isolation, easy fabrication and integration with other circuits.
112 citations
TL;DR: In this paper, a high fMAX InP HEMT transistors in a 5-stage coplanar waveguide integrated circuit were used for low noise amplification at 0.67 GHz.
Abstract: In this letter, low noise amplification at 0.67 THz is demonstrated for the first time. A packaged InP High Electron Mobility Transistor (HEMT) amplifier is reported to achieve a noise figure of 13 dB with an associated gain greater than 7 dB at 670 GHz using a high fMAX InP HEMT transistors in a 5 stage coplanar waveguide integrated circuit. A 10-stage version is also reported to reach a peak gain of 30 dB. These results indicate that InP HEMT integrated circuits can be useful at frequencies approaching a terahertz.
TL;DR: In this paper, a novel ultra wideband band-pass filter with dual sharply rejected notch-bands based on a simplified composite right/left-handed (SCRLH) resonator is presented.
Abstract: This letter presents a novel ultra-wideband (UWB) band-pass filter (BPF) with dual sharply rejected notch-bands based on a simplified composite right/left-handed (SCRLH) resonator. The basic UWB BPF is comprised of four folded shunt quarter-wavelength short-circuited stubs separated by connecting lines with length of λg0/4 and λg0/2, respectively. The SCRLH resonator is studied and employed to introduce the dual notched bands. Good insertion/return losses are achieved as demonstrated in both simulation and experiment.
TL;DR: InAs/AlSb/AlGaSb heterojunction backward diodes are promising detectors for millimeter-wave imaging applications due to their high sensitivity, low noise, and high cutoff frequency as mentioned in this paper.
Abstract: InAs/AlSb/AlGaSb heterojunction backward diodes are promising detectors for millimeter-wave imaging applications due to their high sensitivity, low noise, and high cutoff frequency. By using a device heterostructure with a thin (11 Å) barrier layer, δ-doped cathode, and optimized AlxGa1-xSb anode composition (x=12%), in conjunction with submicron (0.4×0.4 μm2) active area, fabricated detectors have demonstrated DC curvatures of -47 V-1 and record unmatched sensitivities of 4600 V/W at 94 GHz. Impedance-matched sensitivities of 49,700 V/W at 94 GHz are projected from on-wafer S-parameter and sensitivity measurements. These detectors have measured junction resistances of 814 Ω·μm2 and capacitances of 15 fF/μm2. A record low NEPmin of 0.18 pW/Hz1/2 has been projected under conjugate matching conditions. This study demonstrates the potential of Sb-heterostructure backward diodes as ultra-low-noise millimeter-wave direct detectors.
TL;DR: In this paper, a wideband differential-mode bandpass filter (BPF) with good common-mode suppression is proposed on microstrip line for ultra wideband (UWB) application.
Abstract: A novel highly selective wideband differential-mode bandpass filter (BPF) with good common-mode suppression is proposed on microstrip line for ultra-wideband (UWB) application. The initial BPF is similar to a two-stage branch-line structure in geometry and its improved one is formed by stretching the two vertical arms on the input and output ports from λg /4 to 3 λg /4. The aim is to achieve better filter selectivity by adding two additional transmission zeros from the extended arms. In our design, a symmetrical filter with two pairs of external ports is firstly decomposed into two bisections with two single ports under differential- and common- mode excitations. Our study shows that the two-port bisection circuits achieve bandpass and bandstop filtering performances under the differential- and common-mode operation in the lower UWB band, i.e., 3.1-5.1 GHz. The wideband differential-mode BPF is then designed and fabricated. All the three sets of results from the simulations based on the circuit model, fullwave software, and actual measurement are found in good agreement with one another. A highly selective differential-mode passband is achieved in the frequency range of 2.8-5.3 GHz, with a common-mode suppression of about 20 dB.
TL;DR: In this article, an ultrawideband (UWB) bandpass filter with a band notch is proposed, which is realized by cascading a distributed high pass filter and an elliptic low pass filter with an embedded stepped impedance resonator (SIR).
Abstract: In this letter, an ultrawideband (UWB) bandpass filter with a band notch is proposed. The UWB BPF (3.1-10.6 GHz) is realized by cascading a distributed high-pass filter and an elliptic low-pass filter with an embedded stepped impedance resonator (SIR) to achieve a band notch characteristic. The notch band is obtained at 5.22 GHz. It is shown that the notch frequency can be tuned by changing the impedance ratio of the embedded SIR. A fabricated prototype of the proposed UWB bandpass filter is developed. The inband and out-of-band performance obtained by measurement, EM simulation, and that with an equivalent circuit model are in good agreement.
TL;DR: Fractional order circuit elements (inductors and capacitors) based impedance matching networks are introduced for the first time in this article, where all the Smith chart circles (resistance and reactance) are actually pairs of completely identical circles.
Abstract: Fractional order circuit elements (inductors and capacitors) based impedance matching networks are introduced for the first time. In comparison to the conventional integer based L-type matching networks, fractional matching networks are much simpler and versatile. Any complex load can be matched utilizing a single series fractional element, which generally requires two elements for matching in the conventional approach. It is shown that all the Smith chart circles (resistance and reactance) are actually pairs of completely identical circles. They appear to be single for the conventional integer order case, where the identical circles completely overlap each other. The concept is supported by design equations and impedance matching examples.
TL;DR: In this paper, a broadside-coupled structure is utilized to design balanced bandpass filter (BPF) with ultrawideband performance, which shows a 123% fractional bandwidth centered at 6.55 GHz, a sharp and wide upper stopband that extends beyond 20 GHz, and a sharp lower stopband.
Abstract: A broadside-coupled structure is utilized to design balanced bandpass filter (BPF) with ultrawideband performance. The top and bottom layers of the structure contain tapered microstrip patches. Those patches are coupled via tapered slots in the ground plane, which is located at the middle layer. The employed structure operates as a BPF in the differential-mode, whereas it operates as an all-stop filter in the common-mode. The simulated and measured performance of the filter show a 123% fractional bandwidth centered at 6.55 GHz, a sharp and wide upper stopband that extends beyond 20 GHz, and a sharp lower stopband. The filter suppresses the common-mode signals by more than 27 dB in the simulations and 24 dB in the measurements across the whole above mentioned band. The designed filter reveals a distortionless performance in the time domain with only 0.1 ns peak-to-peak variation in the group delay across the band 3.1 to 10.6 GHz.
TL;DR: In this article, a triple/quad-mode stub-loaded resonator was proposed and analyzed for application in bandpass filters (BPFs), where a pair of identical open-ended stubs, shorter than λ/2, were tap-connected to a λ 2 resonator at two symmetrical positions with respect to its center.
Abstract: In this letter, a class of triple-/quad-mode stub-loaded resonators is proposed and analyzed for application in bandpass filters (BPFs). First, a pair of two identical open-ended stubs, shorter than λ/2, are tap-connected to a λ/2 resonator at two symmetrical positions with respect to its center. It results to excite three resonant modes closely to each other while producing a transmission zero above its resonant frequencies. Next, a single open-ended stub, longer than λ/2, is introduced at the center of the resonator. This arrangement is made to bring out a fourth resonant mode approaching the above three modes while causing a transmission zero below all of them. As such, a quad-mode resonator, self-contained with two transmission zeros, is theoretically constituted. Finally, the triple- and quad-pole BPFs with miniaturized size and sharpened roll-off skirts are designed and fabricated to provide an experimental validation on the predicted performances of the proposed filters.
TL;DR: In this article, a tunable microstrip bandpass filter (BPF) with two independently adjustable transmission zeros (TZs) is reported, which can be separately adjusted within a broad tuning range by varying the dc bias voltages applied to the varactors.
Abstract: In this letter, a tunable microstrip bandpass filter (BPF) with two independently adjustable transmission zeros (TZs) is reported. By introducing two microwave varactors to tune the TZs, the center frequency and the bandwidth of the BPF can be separately adjusted within a broad tuning range by varying the dc bias voltages applied to the varactors. Theoretical analysis and design approach are described. The experimental result of a demonstrative BPF shows that a less than 4 dB insertion loss, a relative bandwidth of 9% and a center frequency tunable from 1.4 to 2 GHz are obtained. The measured performance of the fabricated filter shows good agreement with the proposed theory.
TL;DR: In this article, a quintuple-mode ultra-wideband (UWB) bandpass filter (BPF) using a multiple-stub-loaded resonator, consisting of multiple loaded stubs to a uniform transmission-line resonator is presented.
Abstract: This letter presents a quintuple-mode ultra-wideband (UWB) bandpass filter (BPF), using a multiple-stub-loaded resonator, consisting of multiple loaded stubs to a uniform transmission-line resonator, i.e., two asymmetrical stepped-impedance stubs at the center and four uniform-impedance stubs at the symmetrical side locations. Six modes including two odd and four even modes are controllable, while the first five modes are allocated within the UWB band. Two transmission zeros generated by the asymmetrical stepped-impedance stub are used to improve the passband selectivity greatly. The resonant mode and transmission zero chart are given, indicating that the higher modes could be suppressed by the transmission zeros generated by the stubs and the parallel-coupled lines. A compact planar UWB BPF is simulated, fabricated and measured, and the 20 dB stopband performance is extended to 29.7 GHz.
TL;DR: In this article, a dual-mode dual-band bandpass filter using a patch resonator with a cross slot and two different groups of stubs loaded is presented, which can modify the filter's input impedance at different frequencies and control the even and odd modes in the passbands, respectively.
Abstract: This letter presents a dual-mode dual-band bandpass filter using a patch resonator with a cross slot and two different groups of stubs loaded. The cross slot with different orthogonal lengths excites orthogonal modes in the passbands and reduces the patch size. Meanwhile, the two sets of stubs can modify the filter's input impedance at different frequencies and control the even and odd modes in the passbands, respectively. Utilizing these two kinds of elements, transmission poles can be realized easily in both passbands. For demonstration, a dual-band patch resonator filter working at 2.4 and 5.2 GHz is designed. The theoretical analysis is given and the simulated and measured results are presented. The good agreement verifies the proposed method.
TL;DR: Experimental results show that the proposed technique bounds the adjacent channel power ratio to lower than -46 dBc, which is more than 12 dB improvement for both bands concurrently.
Abstract: This letter reports a two-dimensional digital predistortion technique to compensate for the nonlinearity of a concurrent dual band PA. Two different multi-carrier WCDMA signals with more than 1 GHz frequency spacing are concurrently employed to drive the PA and verify the linearization performance. Experimental results show that the proposed technique bounds the adjacent channel power ratio to lower than -46 dBc, which is more than 12 dB improvement for both bands concurrently.
TL;DR: In this article, a compact microstrip quadruplexer with high isolation is presented, which consists of a distributed coupling feeding line, output feeding lines, and uniform resonator pairs.
Abstract: A compact microstrip quadruplexer with high isolation is presented in this letter. The quadruplexer consists of a distributed coupling feeding line, output feeding lines and uniform resonator pairs. Since the uniform resonators would resonate at multiple fundamental frequencies, to obtain a high-isolation quadruplexer, the resonators are properly located with respect to the input and output feeding lines to suppress the harmonic responses. Furthermore, because each pair of resonators control a specific channel frequency independently and the loading effect among channels is very small, the proposed quadruplexer has flexible passband frequencies.
TL;DR: In this article, the first demonstration of in-phase power-combined frequency multipliers above 100 GHz based on a dual-chip single-waveguide topology is presented, which consists of two integrated circuits symmetrically placed along the E-plane of a single transmission waveguide.
Abstract: This work represents the first demonstration of in-phase power-combined frequency multipliers above 100 GHz based on a dual-chip single-waveguide topology, which consists of two integrated circuits symmetrically placed along the E-plane of a single transmission waveguide. This strategy increases by a factor of 2 the maximum sustainable input power with regard to traditional waveguide multipliers. A biasless 190 GHz Schottky doubler based on this novel concept has been designed and tested with a 6-10% conversion efficiency measured across a 177-202 GHz band when driven with a 50-100 mW input power at 300 K.
TL;DR: In this paper, a set of miniaturized dual-band bandpass filters with a quadruple-folded substrate integrated waveguide (SIW) implemented into each design is presented.
Abstract: A set of miniaturized dual-band bandpass filters is presented with a quadruple-folded substrate integrated waveguide (SIW) implemented into each design. They were fabricated using standard low temperature co-fired ceramic (LTCC) technology. The bandwidths of both passbands of the filters are adjustable independently by changing the geometrical parameters of the coupling structure. Two filter samples are demonstrated with central frequencies located at 2.4/5.2 and 2.4/5.7 GHz, respectively, and their measured S-parameters agree well with the simulated ones.
TL;DR: In this article, a planar and compact phase shifters with broadband characteristics are presented, which utilize broadside-coupled microstrip-coplanar waveguide, and thus the proposed devices can be fabricated using the simple and cheap double-side printed circuit boards.
Abstract: A method to design planar and compact phase shifters with broadband characteristics is presented. It utilizes broadside-coupled microstrip-coplanar waveguide, and thus the proposed devices can be fabricated using the simple and cheap double-side printed circuit boards. The method is used to design 60° and 90° phase shifters. The simulated and measured results show that the developed phase shifters achieve 3 to 11 GHz bandwidth with low phase instability (±2°), very low insertion loss (0.4 dB), high return loss (15 dB), and a compact size (1.5 cm × 2 cm).
TL;DR: In this paper, a modified Gysel power divider (PD) is modified to achieve unequal or equal power division and suitability for three arbitrary real terminated impedances without any transmission losses.
Abstract: The Gysel power divider (PD) is modified to achieve unequal or equal power division and suitability for three arbitrary real terminated impedances without any transmission losses in this letter. The calculation of electrical parameters in this asymmetrical structure is flexible. Meanwhile, this modified Gysel PD maintains high power-handling advantage over Wilkinson PD. By using the transmission line theory, the simple closed-form design equations are available for evaluation of these circuit parameters. For verification, two microstrip examples, which include an equal Gysel PD with three different output-port impedances and an unequal one for three standard 50-Ω ports without additional output-port transformers, are given. It can be observed that there is excellent agreement between the simulated and measured results.
TL;DR: In this paper, a generalized Smith chart is introduced to represent fractional order circuit elements and a graphical technique supported by the analytical method is presented to plot impedances on the fractional Smith chart.
Abstract: For the first time, a generalized Smith chart is introduced here to represent fractional order circuit elements. It is shown that the standard Smith chart is a special case of the generalized fractional order Smith chart. With illustrations drawn for both the conventional integer based lumped elements and the fractional elements, a graphical technique supported by the analytical method is presented to plot impedances on the fractional Smith chart. The concept is then applied towards impedance matching networks, where the fractional approach proves to be much more versatile and results in a single element matching network for a complex load as compared to the two elements in the conventional approach.
TL;DR: In this paper, a photonic approach was proposed to generate a phase-coded mm-wave signal with large frequency tunability using a Mach-Zehnder modulator that is biased at the maximum transmission point and an optical notch filter.
Abstract: A photonic approach to generating a phase-coded millimeter-wave (mm-wave) signal with large frequency tunability is proposed and demonstrated. Two ± second-order optical sidebands are generated by using a Mach-Zehnder modulator that is biased at the maximum transmission point and an optical notch filter. A polarization-maintaining fiber Bragg grating is then utilized to make the two sidebands orthogonally polarized. By sending the two orthogonally polarized sidebands to a polarization modulator, to which a phase-coding signal is applied, a frequency-quadrupled phase-coded mm-wave signal is generated. The generation of a phase-coded mm-wave signal with tunable frequencies at 40, 42, and 50 GHz is experimentally demonstrated. A pulse compression ratio of about 128 is achieved.
TL;DR: In this article, an accurate closed-form formula is derived from an analytical method to calculate dispersion properties of the substrate integrated waveguide (SIW), which is used to accurately estimate the cutoff frequency of the dominant mode at a low leakage condition.
Abstract: An accurate closed-form formula is derived from an analytical method to calculate dispersion properties of the substrate integrated waveguide (SIW). The derived equation which is a function of geometrical parameters is used to accurately estimate the cutoff frequency of the dominant mode at a low leakage condition. The unit cell of an SIW can be considered as two consecutive rectangular waveguide sections with the specific difference in their widths. The propagation constant is extracted by applying the Floquet theorem to the overall transmission matrix of the single unit cell. The proposed formula agrees well with numerical solutions as well as reported empirical equations in a wide range of structure parameters.