Showing papers in "IEEE Microwave and Wireless Components Letters in 2014"
TL;DR: In this paper, a planar complementary split-ring resonator (CSRR) was used to measure the dielectric constants and loss tangents of material under test (MUT) using the equivalent RLC resonator circuit model.
Abstract: A noninvasive planar complementary split-ring resonator (CSRR) for measuring the dielectric constants and loss tangents of material is presented in this letter. Measurements were developed to extract the complex permittivity of the material under test (MUT) using the equivalent RLC resonator circuit model. This technique enables a single-step measurement of the MUT without the need for machining or reshaping. The method requires calculating only two parameters, the resonant frequency (fr) and the magnitude (dB) response, thus achieving a substantial reduction in cost and computation time. A CSRR sensor operating in the 1.8 to 2.8 GHz band is fabricated and tested for verification. The measurement errors in the dielectric constant were less than 7.6%. An efficient technique of CSRR measuring complex permittivity is experimentally verified.
187 citations
TL;DR: This work shows how using specifically selected or designed waveforms in wireless power transfer systems can lead to improved RF to dc conversion efficiency in rectifier circuits in the receiving end of these systems.
Abstract: This work shows how using specifically selected or designed waveforms in wireless power transfer (WPT) systems can lead to improved RF to dc conversion efficiency in rectifier circuits in the receiving end of these systems Signals with different time domain waveforms are considered such as OFDM, white noise and chaotic waveforms, and the performance of a rectifier circuit operating at 433 MHz is evaluated when using these signals in comparison to a single carrier constant envelope signal The performed experiments show that selecting high peak to average power ratio (PAPR) signals lead to improved RF-DC conversion efficiency in rectifier circuits
183 citations
TL;DR: In this article, a compact microstrip diplexer for UMTS and WCDMA system is proposed, which is mainly composed of three dual-mode stub-loaded microstrip resonators.
Abstract: A novel compact microstrip diplexer for UMTS and WCDMA system is proposed in this letter. The diplexer is mainly composed of three dual-mode stub-loaded microstrip resonators. Two resonant modes of a stub-loaded resonator work together with one mode produced by the common stub-loaded resonator to form a passband or operating band of the proposed diplexer. Extensive study is then conducted on coupling scheme involved in various parts of the diplexer. In particular, the resonance of a resonator is employed to create a desired transmission zero in the stopband, thus improving the isolation between two passbands. The proposed diplexer is in final fabricated and measured. A good agreement between EM simulated and measured results evidently validates the proposed methodology.
149 citations
TL;DR: In this paper, a new type of microstrip quarter-wavelength stepped-impedance resonator (SIR) filter with controllable mixed electric and magnetic coupling is proposed.
Abstract: This letter proposes a new type of microstrip quarter-wavelength stepped-impedance resonator (SIR) filter with controllable mixed electric and magnetic coupling. A conducting pin and an open gap between two coupled SIRs are jointly used to create the mixed coupling, and the electric and magnetic coupling can be separately controlled by adjusting the spacing between the gap and the position of the conducting pin. Based on the proposed structure, a second-order filter and a third-order filter are designed and fabricated. Good agreement between the measured and simulated data is obtained.
90 citations
TL;DR: In this article, a compact and high isolation microstrip filtering power dividers with second-order Chebyshev filtering response have been presented. And the measured results are in good agreement with the simulated predictions, showing that better than 30 dB isolation within the whole passband is achieved with a tradeoff of the bandwidth.
Abstract: Compact and high isolation microstrip filtering power dividers (PDs) have been presented in this letter. In order to effectively reduce circuit area, the compact folded net-type resonator is selected to build up the resonator-based PDs with a filtering response. The highly symmetric structure of the divider provides not only a good in-band isolation performance, but also a low magnitude imbalance and phase imbalance. For the demonstration, two design examples of in-phase and out-of-phase PDs with second-order Chebyshev filtering response have been designed and fabricated with microstrip technology. As a result, both dividers have an extremely small size of 0.19 λg by 0.19 λg. The measured results are in good agreement with the simulated predictions, showing that better than 30 dB isolation within the whole passband is achieved with a tradeoff of the bandwidth.
85 citations
TL;DR: In this paper, a bandpass filter with dual notched bands using triangular defected ground structures (DGS) was proposed, and two symmetrical dumbbell-shaped interdigital capacitors were formed to improve the BPF's performance.
Abstract: This letter proposes a novel ultra-wideband (UWB) bandpass filter (BPF) with dual notched bands using triangular defected ground structures (DGS). Two symmetrical dumbbell-shaped interdigital capacitors are formed to improve the BPF's performance. Three pairs of tapered defected ground structures are studied and adopted to suppress the spurious passband by assigning their transmission zeros towards the out of band signal. A small UWB BPF is obtained by combining these two structures. One of the arms in coupled-line sections is extended and folded to create a notched band at 5.3 GHz, and a meander line slot is developed to create another notched band at 7.8 GHz. Simulated and measured results are in good agreement indicating that the proposed BPF has a passband from 2.8 to 11.0 GHz and a wide stopband bandwidth with 20 dB attenuation up to 30.0 GHz.
83 citations
TL;DR: In this article, a series of continuous modes for designing broadband high-efficiency power amplifiers (PAs) are proposed, which extend the continuous mode concept, and the impedance solutions space based on these modes offer a greater freedom for realizing broadband high efficiency PAs.
Abstract: In this letter, a series of continuous modes for designing broadband high-efficiency power amplifiers (PAs) are proposed, which extend the continuous mode concept. The impedance solutions space based on these modes offer a greater freedom for realizing broadband high-efficiency PAs. To verify this theory, a high-efficiency PA over a 54.5% bandwidth from 1.6 to 2.8 GHz is designed. The simulated results show that the fundamental impedances in this PA are found to be in good agreement with the calculated ones. Moreover, this PA delivers average output power of 14.2 W with an average drain efficiency of 75.7% in the target band.
80 citations
TL;DR: In this paper, a compact balanced-to-balanced microstrip diplexer with high isolation and common-mode suppression is proposed for wireless local area networks (WLAN) and worldwide interoperability for microwave access (WiMAX) applications simultaneously.
Abstract: In this letter, a compact balanced-to-balanced microstrip diplexer with high isolation and common-mode (CM) suppression is proposed for wireless local area networks (WLAN) and worldwide interoperability for microwave access (WiMAX) applications simultaneously. The proposed diplexer is designed via the combination of two balanced bandpass filters (BPF) without extra junction matching network. Both BPFs are composed of uniform impedance resonators (UIR) and short- ended microstrip parallel-coupling feedlines. Finally, the proposed diplexer is fabricated and measured. The measured differential-mode (DM) isolation in the two passbands is more than 33 dB. While for the CM signal, the insertion loss is below 30 dB in the two operation bands. The simulated and measured results exhibit a satisfactory agreement to validate the proposed configuration. The diplexer size is only 0.26λg ×0.38λg, where λg is the guided wavelength at 2.45 GHz.
73 citations
TL;DR: A bandpass Wilkinson power divider with a wide stopband with a three-terminal and two-pole bandpass filter and two lowpass filters is proposed in this letter.
Abstract: A bandpass Wilkinson power divider with a wide stopband is proposed in this letter. A three-terminal and two-pole bandpass filter and two lowpass filters are employed to substitute two quarter-wavelength transformer in the conventional Wilkinson power divider. The proposed divider achieves not only bandpass response but also a very wide stopband. The rejection is greater than 20 dB up to 22.2 f0. Experiments are carried out to validate design concept of the proposed power divider.
68 citations
TL;DR: In this article, a double-pulse technique for the dynamic characterization of GaN FETs is presented, which is shown to be not only isothermal but also corresponding to a fixed charge trapping state.
Abstract: Standard dynamic characterization methods based on periodic narrow-pulse low duty-cycle excitation waveforms provide suboptimal I/V curves when used along with GaN field effect transistors (FETs), due to complex nonlinear charge trapping effects. Thus, a double-pulse technique for the dynamic characterization of GaN FETs is here presented. The double-pulsed I/V characteristics are shown to be not only isothermal but also corresponding to a fixed charge trapping state.
66 citations
TL;DR: In this article, a novel compact structure for dual-band Wilkinson power divider has been proposed, which consists of a single line, two coupled lines and four lumped elements.
Abstract: A novel compact structure for dual-band Wilkinson power divider has been proposed. The power divider consists of a single line, two coupled lines and four lumped elements. Using even- and odd-mode analysis, the design equations have been obtained through rigorous derivation. The odd-mode impedance Z o is a free variable here, it can be used to control the coupling between the coupled lines, as well as the values of the inductor and capacitor. This provides much flexibility and convenience to our design. Moreover, it significantly widens the frequency ratio to be 10 or even more.
TL;DR: A planar 4-way power divider with bandpass filtering response based on the coupled line is presented and comparison of the measured and simulated results is presented to verify the theoretical predications.
Abstract: A planar 4-way power divider with bandpass filtering response based on the coupled line is presented. Its frequency response is similar to a coupled line filter. Moreover, open stubs are utilized to get good frequency selectivity by introducing transmission zeros and improve input match. Three isolation resistors are used to satisfy both transmission and isolation property. The equivalent even- and odd-mode circuits of the power divider are analyzed, while the design equations are derived. Comparison of the measured and simulated results is presented to verify the theoretical predications.
TL;DR: In this article, the authors proposed a compact 4 $\times$ 4 Butler matrix using only microstrip couplers and a crossover, which avoided the interconnecting mismatch loss and imbalanced amplitude introduced by the phase shifter.
Abstract: A novel compact 4 $\times$ 4 Butler matrix using only microstrip couplers and a crossover is proposed in this letter. Compared with the conventional Butler matrix, the proposed one avoids the interconnecting mismatch loss and imbalanced amplitude introduced by the phase shifter. The measurements show accurate phase differences of $45\pm 0.8^{\circ}$ and $-135\pm 0.9^{\circ}$ with an amplitude imbalance less than 0.4 dB. The 10 dB return loss bandwidth is 20.1%.
TL;DR: In this article, the authors proposed a novel design approach of wideband 90° phase shifter, which comprises a stepped impedance open stub (SIOS) and a coupled-line with weak coupling, and the result of analyses demonstrates that the bandwidths of return loss (RL) and phase deviation (PD) can be expanded by increasing the impedance ratio of the SIOS and the coupling strength of the coupled line.
Abstract: This letter proposes a novel design approach of wideband 90 ° phase shifter, which comprises a stepped impedance open stub (SIOS) and a coupled-line with weak coupling. The result of analyses demonstrates that the bandwidths of return loss (RL) and phase deviation (PD) can be expanded by increasing the impedance ratio of the SIOS and the coupling strength of the coupled-line. For RL > 10 dB, insertion loss (IL) 1.1 dB, and PD of ±5°, the fabricated microstrip single-layer phase shifter exhibits bandwidth of 105% from 0.75 to 2.4 GHz.
TL;DR: In this article, a dual-band filter using half-mode substrate integrated waveguide (HMSIW) resonators is presented, which achieves good selectivity and high out-of-band rejection.
Abstract: A compact dual-band filter using half-mode substrate integrated waveguide (HMSIW) resonators is presented in this letter. Dual-band response is achieved by the quasi-TEM mode and the TE102 mode of the novel HMSIW resonator. Slotline perturbation is introduced to adjust the resonant frequency of the TE102 mode, while it has little effect on the performance of the quasi-TEM mode. Source-load coupling is utilized to obtain good selectivity and high out-of-band rejection. A dual-band filter is designed, fabricated and measured to demonstrate the proposed method. The simulated and measured results show reasonable agreement.
TL;DR: In this article, a low noise-figure (NF) and high power gain (S21) 3 ~ 10 GHz ultra-wideband low-noise amplifier (UWB LNA) with excellent phase linearity using 0.18 μm CMOS technology is reported.
Abstract: A low noise-figure (NF) and high power gain (S21) 3 ~ 10 GHz ultra-wideband low-noise amplifier (UWB LNA) with excellent phase linearity using 0.18 μm CMOS technology is reported. An enhanced π-match input network is used to achieve wideband input impedance matching as well as high and flat S21. To achieve low and flat NF, the pole frequency and pole quality factor of the second-order NF frequency response are tuned to approximate the maximally flat condition. The LNA consumes 18 mW, achieving S11 better than -10 dB for frequency lower than 12.2 GHz and group-delay (GD) variation smaller than ±14.6 ps for frequencies 3 ~ 10 GHz. Additionally, high and flat S21 of 13.7 ± 1.5 dB is achieved for frequencies 1 ~ 12.5 GHz, which means the corresponding 3-dB bandwidth is 11.5 GHz. Furthermore, the LNA achieves minimum NF of 2.2 dB at 4 GHz and NF of 2.3 ± 0.1 dB for frequencies of 3 ~ 10 GHz, one of the best NF results ever reported for a 3 ~ 10 GHz CMOS LNA.
TL;DR: In this paper, a dual-band balun bandpass filter (BPF) with high selectivity is proposed and implemented by taking advantage of the existence of multiple substrate integrated waveguide (SIW) cavity modes.
Abstract: A new method of designing a dual-band balun bandpass filter (BPF) with high selectivity is proposed and implemented by taking advantage of the existence of multiple substrate integrated waveguide (SIW) cavity modes. The major design concept applied in this letter is based on two mechanisms: one is by properly placing the output ports to achieve the balanced output for both passbands, and the other is by taking cross coupling of higher/lower order modes to achieve transmission zeros (TZs) at each side of the passband. Two internal coupling slots are involved to separately control the coupling level between cascaded cavities for each passband. A prototype operating at $9.0~{\rm GHz}$ and $9.8~{\rm GHz}$ has been realized and shows the desired filtering performance. The differences between the two outputs are within $180^{\circ}\pm 2^{\circ}$ in phase and $0.6~{\rm dB}$ in magnitude across the two passbands. Measured frequency responses agree well with the simulated ones in this work.
TL;DR: In this article, a triple-band bandpass filter with good selectivity based on modified grounded stepped impedance resonators (SIRs) is presented, where the fundamental and first higher order resonances of the two $\lambda/4$ grounded SIRs are utilized to obtain dual-band response.
Abstract: A triple-band bandpass filter with good selectivity based on modified grounded stepped impedance resonators (SIRs) is presented. The fundamental and first higher order resonances of the two $\lambda/4$ grounded SIRs are utilized to obtain dual-band response. Moreover, bandwidths of the two passbands can be controlled by tuning the distance between the two grounded vias. Owing to the use of two $\lambda/2$ fork resonators, another passband can be realized without increasing additional feedlines, which can be designed independently while other passbands are not affected. Several transmission zeros (TZs) are generated on each side of the passbands to obtain good selectivity. The $\lambda/4$ SIRs are embedded inside of the $\lambda/2$ fork resonators to realize miniaturization. The measurement and simulation results show good agreement.
TL;DR: In this paper, the authors presented the analysis, implementation and experimental results of a broadband highly efficient power amplifier (PA) using harmonic-tuned method for long-term evolution (LTE)-advanced application.
Abstract: This letter presents the analysis, implementation and experimental results of a broadband highly efficient power amplifier (PA) using harmonic-tuned method for long-term evolution (LTE)-advanced application. Load-pull simulation has been employed to obtain the optimal load impedances, especially the second harmonic impedances, for high efficiency and output power over wide bandwidth. A stepped-impedance low-pass matching network was then designed to achieve the desired impedance transformation. Experimental results show that the PA achieves 64%-76% efficiency and higher than 40 dBm output power over the frequency band from 2 to 3.5 GHz. When driven by a 100 MHz LTE-advanced signal at an average output power of 33.5 dBm, the average efficiency of 33.8%, 34.9%, and 37.8% was measured at 2.15, 2.55, and 3.45 GHz, respectively. The corresponding adjacent channel leakage ratio can be linearized to about -48 dBc by using digital pre-distortion technique.
TL;DR: In this paper, a triple-passband, dual-stopband filter consisting of six cascaded singlets is introduced in substrate integrated waveguide (SIW) technology, each singlet produces one independent transmission zero (TZ).
Abstract: A triple-passband, dual-stopband filter consisting of six cascaded singlets is introduced in substrate integrated waveguide (SIW) technology. Each singlet produces one independent transmission zero (TZ). Four of six TZs are placed within the filter passband, producing three passbands separated by two stopbands. The corresponding coupling matrix is synthesized based on a combination of well-known analytic and optimization methods. The SIW filter is designed for stopbands centered at 10.25 and 11.23 GHz, and passbands at 9.72, 10.76, and 11.76 GHz. The prototype is fabricated and measured. Good agreement between simulated and measured results is achieved.
TL;DR: In this paper, a cross-coupling between the first and last short-circuited stubs is introduced to obtain new pairs of transmission zeros on both sides of the passband.
Abstract: Two novel, compact, and highly frequency selective ultra-wideband (UWB) bandpass filters (BPFs) based on an improved model are presented in this letter. The improved model contains four short-circuited stubs connected by transmission lines. A cross-coupling between the first and last short-circuited stubs is introduced to obtain new pairs of transmission zeros on both sides of the passband. The relationship between the coupling factor and the position of the transmission zeros was analyzed and good agreement was obtained between the analysis and model simulation results. Based on the model, two UWB BPFs are designed with 51% (3.1 to 5.2) GHz and 108% (3 to 10) GHz relative bandwidth and small size of 15 mm × 15 mm and 19 mm × 14 mm, respectively. The insertion loss of the (3.1 to 5.2) GHz filter is less than 0.4 dB in passband and the other one is less than 3 dB. The simulation and measurement results agree well.
TL;DR: In this paper, a millimeter-wave bandpass filter (BPF) using substrate integrated waveguide (SIW) is proposed, where three resonators are formed by etching slots on the top metal plane of the single SIW cavity.
Abstract: A millimeter-wave (mmW) bandpass filter (BPF) using substrate integrated waveguide (SIW) is proposed in this work. A BPF with three resonators is formed by etching slots on the top metal plane of the single SIW cavity. The filter is investigated with the theory of electric coupling mechanism. The design procedure and design curves of the coupling coefficient (K) and quality factor (Q) are given and discussed here. The extracted K and Q are used to determine the filter circuit dimensions. In order to prove the validity, a SIW BPF operating at 140 GHz is fabricated in a single circuit layer using low temperature co-fired ceramic (LTCC) technology. The measured insertion loss is 1.913 dB at 140 GHz with a fractional bandwidth of 13.03%. The measured results are in good agreement with simulated results in such high frequency.
TL;DR: In this article, a step-impedance ring resonator (SIRR) with two pairs of shorted stubs is proposed to design a dual-band bandpass filter.
Abstract: A novel stepped-impedance ring resonator (SIRR) with two pairs of shorted stubs is proposed to design a dual-band bandpass filter. The proposed resonator is a quad-mode resonator, and one resonator can realize a dual-band filter. The frequency space between two passbands and bandwidths of two passbands can be controlled by the shorted stubs. Wide out-of-band rejection can be achieved by selecting the desired impedance and length ratios and suitable feeding point to suppress some spurious resonant frequencies. A prototype filter centered at 1.395 and 1.825 GHz is designed with the first spurious response occurring at 7.84 GHz or $5.7f_{01}$ ( $f_{01}$ is the center frequency of the first passband). Good agreement between the simulated and measured results can be observed.
TL;DR: In this paper, an inverter-based inductorless single-to-differential (S2D) wideband low-noise amplifier (LNA) was proposed.
Abstract: This study presents an inverter-based inductorless single-to-differential (S2D) wideband low-noise amplifier (LNA). The proposed LNA has three inverter-based gain stages with a global shunt feedback resistor for wideband input impedance matching. Moreover, a shunt capacitor with a current bias transistor in the third gain stage enhances the gain/phase imbalances and the linearity of the pseudo-differential outputs. When implemented in a TSMC $0.18$ - $\mu {\rm m}$ CMOS process, this wideband LNA covering DC-1.4 GHz achieves a ${\rm S}_{21}$ of 16.4 dB, a minimal input third-order intercept point (IIP3) of $ -13.3~{\rm dBm}$ , and a minimal noise figure (with output buffers) of 3 dB. The output gain and phase imbalances are less than 1 dB and 2.5 $^{\circ}$ , respectively, within 1 GHz. The chip consumes 12.8 mW from a 1.8 V supply.
TL;DR: In this paper, a X-band GaN monolithic microwave integrated circuits (MMIC) high power Amplifier (HPA) suitable for future generation Synthetic Aperture Radar systems is presented.
Abstract: A X-band GaN monolithic microwave integrated circuits (MMIC) High Power Amplifier (HPA) suitable for future generation Synthetic Aperture Radar systems is presented. The HPA delivers 14 W of output power, more than 38% of PAE in the frequency bandwidth from 8.8 to 10.4 GHz. Its linear gain is greater than 25 dB. For the first time an MMIC X-band HPA has been designed by directly measuring the transistor behavior at the current generator plane. In particular, optimum device load-line has been selected according to the chosen performance tradeoffs.
TL;DR: In this article, the authors demonstrate two 94 GHz SPDT quarter-wave shunt switches using saturated SiGe HBTs, which achieved an insertion loss and isolation at 94 GHz of 1.8 dB and 19.3 dB, respectively.
Abstract: This work demonstrates two 94 GHz SPDT quarter-wave shunt switches using saturated SiGe HBTs. A new mode of operation, called reverse saturation, using the emitter at the RF output node of the switch, is utilized to take advantage of the higher emitter doping and improved isolation from the substrate. The switches were designed in a 180 nm SiGe BiCMOS technology featuring 90 nm SiGe HBTs (selective emitter shrink) with fT/fmax of 250/300+ GHz. The forward-saturated switch achieves an insertion loss and isolation at 94 GHz of 1.8 dB and 19.3 dB, respectively. The reverse-saturated switch achieves a similar isolation, but reduces the insertion loss to 1.4 dB. This result represents a 30% improvement in insertion loss in comparison to the best CMOS SPDT at 94 GHz.
TL;DR: In this article, a broadband air-filled rectangular waveguide to substrate integrated waveguide (SIW) transition at V-band is proposed, where an aperture coupled patch antenna structure is incorporated into the design.
Abstract: A broadband air-filled rectangular waveguide to substrate integrated waveguide (SIW) transition is proposed at V-band. By introducing an aperture coupled patch antenna structure into the design, a bandwidth wider than 35% for |S
11
| <; -10 dB is achieved. A back-to-back prototype fabricated by the low-cost printed circuit board (PCB) technology shows that the insertion loss of a single transition is less than 0.58 dB within the bandwidth. With good performance and compact volume, the proposed transition is attractive for millimeter-wave circuit designs and measurements.
TL;DR: In this paper, an S-shaped complementary split ring resonator (S-CSRR) was proposed for application in compact differential filters and a circuit model was developed and validated through electromagnetic simulations.
Abstract: This letter presents an S-shaped complementary split ring resonator (S-CSRR) for application in compact differential filters. The working principle of the proposed S-CSRR is explained and a circuit model is developed and validated through electromagnetic simulations. It is shown that an S-CSRR-loaded differential microstrip line with series gaps can be used in the design of compact differential bandpass filters (BPFs) with common-mode suppression. The filter design procedure is explained and the theoretical concept is validated through fabrication and measurement of a compact (0.09λg ×0.25 λg) third-order differential BPF with common-mode suppression.
TL;DR: In this article, a bandpass filter with different load impedances was designed to meet the requirement of PA, and the total size of the proposed design was greatly reduced compared with the classical cascaded PA and filter.
Abstract: This letter presents a novel high efficiency power amplifier (PA) with good bandpass responses. By designing a bandpass filter (BPF) with different load impedances to meet the requirement of PA, good bandpass responses can be exhibited. Compared with the classical cascaded PA and filter, the total size of the proposed design is greatly reduced. Meanwhile, the bandwidth is extended. Two transmission zeros are generated at the passband edges, resulting in high selectivity. For demonstration, a filter-integrated PA prototype is implemented. Both theoretical analysis and measured results are presented for validation.
TL;DR: In this paper, a compact planar phase shifters with wide range of differential phase shift across ultra wideband frequency are proposed, which use broadside coupled structure terminated with open-ended or short-ended stubs.
Abstract: Compact planar phase shifters with wide range of differential phase shift across ultra-wideband frequency are proposed. To achieve that performance, the devices use broadside coupled structure terminated with open-ended or short-ended stubs. The theory of operation for the proposed devices is derived. To validate the theory, several phase shifters are designed to achieve a differential phase ranging from -180° to 180°. Moreover, three prototypes are developed and tested. The simulated and measured results agree well with the theory and show less than 7° phase deviation and 1.4 dB insertion loss across the band 3.1-10.6 GHz.