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This paper presents a low-power 60 GHz low-noise amplifier (LNA) designed for Gbit/s applications using 28 nm CMOS technology. The LNA exploits a single-stage pseudo-differential architecture with integrated input transformer for both electrostatic discharge (ESD) protection and simultaneous noise/impedance matching. An effective power-constrained design strategy is adopted to pursue the lowest current consumption at the minimum noise figure (NF), with the best tradeoff between gain and frequency bandwidth. The LNA, which has been designed to drive an on–off keying (OOK) demodulator, is operated at a supply voltage as low as 0.9 V and achieves a voltage gain of about 21 dB with a 3 dB bandwidth of 2 GHz around 60 GHz. Thanks to the proper impedance transformation at the 60 GHz input, the amplifier exhibits an NF of 6.3 dB, also including the input transformer loss with a very low power consumption of about 5 mW. The adoption of a single-stage topology also allows an excellent input 1 dB compression point (IP1dB) of −4.7 dBm. The input transformer guarantees up to 2 kV human body model (HBM) ESD protection. [ABSTRACT FROM AUTHOR]

The electromagnetic transient (EMT)-type impedance scanning methods conducted in positive sequence domain and dq-frame (p-scan and dq-scan, respectively) have been widely used for identifying inverter-based resource (IBR) instabilities. They obtain the sequence domain single-input single-output (sequence-SISO) and dq-frame multi-input multi-output (dq-MIMO) impedance models of an IBR, respectively. The dq-MIMO impedance-based stability assessment (IBSA) is more accurate compared to the sequence-SISO IBSA as it considers the mirror frequency effect (MFE). However, unlike the sequence-SISO, the dq-MIMO IBSA cannot differentiate the resonance frequency from its mirror frequency, because the dynamics in dq-frame incorporate both the positive and negative sequence impedances of IBR. This paper proposes a new IBSA scheme to eliminate this shortcoming. First, a dq-MIMO IBSA is carried out to obtain the accurate dq-frame resonance frequency and stability margin. Then a sequence-SISO IBSA is conducted to determine the phase domain resonance frequency. The sequence-SISO impedance models are transformed from the dq-MIMO model. The proposed scheme has lower computational costs than the existing dq-MIMO IBSA methods. The effectiveness of the proposed scheme is validated on a test system incorporating full-size converter-based wind park (FSC-based WP). This paper also demonstrates the possibility of weak grid instability occurrence in supersynchronous frequency range.

For the typical magnetically coupled wireless power transmission system, power consumption is often caused by the impedance effect of the primary and secondary sides, the loss and heat generation of the actual semiconductor devices and the change of the coupling coefficient caused by distance. The uncertainty of frequency tracking efficiency caused by high enough coil transmission with low load receiving efficiency and load impedance changes makes it difficult to stabilize the output of the optimal efficiency point of the system. In order to solve this problem, a wireless power transmission system is proposed based on the traditional wireless power transmission system a wireless power transmission system is proposed to predict and stabilize the variable impedance, so as to stably track the efficiency of the system in the resonant frequency range. It is not affected by load jitter, actual circuit parameters and environmental disturbance. The test results show that the transmission efficiency of tracking frequency and predicting impedance can be realized at a certain distance, and the difference between the prediction error and the actual efficiency is about 1%–3%.

Two planar coupled line baluns without vias are designed in this letter. Because of asymmetrical configurations, a virtual port is introduced for even–odd mode analysis, showing the proposed baluns are equivalent to an open‐shorted anti‐coupled line section in odd mode and an open–open coupled line section in even mode. Consequently, bandpass response is obtained in odd mode while suppression is available in even mode, realizing the out‐of‐phase power splitting characteristic. Due to different input and output impedances of the open‐shorted anti‐coupled line sections, the designed baluns have the functionality of impedance transformation, and S‐parameters are then calculated to verify the performance as well. For validation, the two proposed baluns are fabricated with impedance transformers for a 50 Ω test system. The measured results exhibit the two baluns have 16.6% and 18.1% impedance bandwidth centered at 3.5 GHz with an insertion loss of 3.6 and 3.7 dB, respectively. [ABSTRACT FROM AUTHOR]

This letter presents a compact lumped‐element two‐way differential to single‐ended Wilkinson power combiner with embedded impedance transformation. It consists of two transformer baluns and two parallel resistance and capacitor (RC) branches. The two transformers generate high‐order impedance transformation networks at even‐mode operation and form resonators together with the two parallel RC branches at odd‐mode operation, thus achieving broadband impedance matching and power combining with a compact area. A proof‐of‐concept prototype working at 1.7 GHz is designed and fabricated. Measurement results show that the peak isolation is 24.5 dB, insertion loss is from 0.34 to 1.15 dB and magnitude and phase imbalance are within 0.1 dB and 1∘ ${1}^{\circ }$, respectively, over the frequency range from 1.37 to 1.97 GHz. The area is only 6.54 mm × $\times $ 6 mm. [ABSTRACT FROM AUTHOR]

Dielectric sensing based on capacitive measurement technology is a favourable measurement approach in many industries and fields of application. From an electrical point of view, a coupling capacitance must be measured in the presence of stray capacitances. Different receiver circuit structures have been proposed for the underlying displacement current measurement. Ideally, the sensor assembly is directly connected to the sensor circuitry to minimize the influence with respect to these parasitic capacitances. However, under harsh operating conditions, e.g., at high temperatures, the sensor and the receiver circuit must be separated in order to protect the electronics. Consequently, the receiver circuit and the sensor have to be connected by cables, e.g., coaxial cables. The measurement setup differs significantly from the ideal design with a direct connection. In this paper, we investigate the behaviour of three common measurement circuits for capacitive measurements in instrumentations with cables. We study the interaction between the sensor and the electronics and analyse the operating behaviour of the circuit, as well as the operating states of the amplifiers used. We also address cross-sensitivities in the sensor design due to stray capacitances. The analyses are carried out for different cable lengths and measuring frequencies, and conditions for the usability of the circuit are deduced. In addition to the operational behaviour, we also evaluate the circuits by means of a noise analyses. Based on this analysis, we show a direct comparison of the circuits. The analysis is based on simulation studies, as well as collaborative measurements on test circuits where all circuit parameters are provided. The test circuits are realized with dedicated state-of-the-art circuit elements and, together with the analysis approach and the results, thus provide a basis for future developments. [ABSTRACT FROM AUTHOR]

In this paper, the design of a compact broadband lumped-distributed balun, including impedance matching, is suggested. For the broadband impedance characteristic of the suggested balun design, the even-mode impedances of the balun were analyzed using the differential port impedance (Zin). The proposed balun enables broadband impedance matching without an additional impedance-matching network, thereby reducing the circuit size and passive loss. The suggested balun was fabricated using FR4-based PCB and its performance was verified. The balun was designed to match a single-ended port impedance of 50 Ω and a Zin of 25 Ω. The fabricated balun has a -10-dB return loss from 550 to 950 MHz. Zin was measured to confirm impedance transformation and matching of the fabricated balun. The measured real value of impedance was 25±5 Ω and the imaginary value was 0±5 Ω from 640 to 870 MHz. The electrical length of the balun was reduced to 18°. [ABSTRACT FROM AUTHOR]

In this paper, a design methodology for a fully integrated impedance-transforming multi-winding 90° coupler is proposed. The oper- ation of the proposed coupler was verified using measurement results. These couplers were fabricated using the WIN semiconductor InGaP/GaAs heterojunction bipolar transistor (HBT) process. To provide an impedance transformation, the proposed couplers were de- signed with 3, 4 and 5 turn coils for 50-, 75-, and 100-Ω impedance transformations, respectively. The center frequencies of each coupler were 5.5, 3.33, and 2.47 GHz. Two copper metal layers were combined together with a via to attain a high Q factor, and its improve- ment was analyzed. The measurement results show that the insertion losses of the proposed couplers are less than 0.37 dB and phase imbalances are less than 2.74°. [ABSTRACT FROM AUTHOR]

Conducted emission (CE) measurement is essential to integrated circuit (IC) electromagnetic compatibility (EMC) testing, and accurate calibration of testing equipment is the prerequisite for the reliability of IC CE measurement. This paper proposes an ultrawideband Direct-Coupling Probe (DCP) calibration method. It can effectively improve the deficiencies of the calibration method described in standard IEC 61967-4. Impedance matching calibration fixtures were developed, and a de-embedding algorithm based on time domain reflectometry (TDR) and microwave scattering parameter measurement was proposed. This method can theoretically extend the calibration frequency range of DCP to 20 GHz. The experiment verifies the combination of the algorithm and fixtures can effectively suppress the reflection and ripple caused by the impedance mismatch between the instrument system and DCP and improve the accuracy and repeatability of the measurement process. Factors affecting calibration results, such as fixture characteristic impedance, grounding, and time window selection, are also analyzed and discussed. • Proposes an ultrawideband direct-coupled probe calibration method up to 20 GHz. • Designed impedance transformation fixtures for direct-coupling probe calibration. • Proposing innovative ultrawideband de-embedding algorithms for calibrated fixtures. • Effectively suppresses reflection and ripple in high-frequency calibration. • Analyzed the effects of fixture characteristics, grounding, etc., on calibration results. [ABSTRACT FROM AUTHOR]

A soil moisture sensor has been widely used to measure the volumetric water content in soil at present. However, the detection of soil profile moisture sensors is often affected by the air and wiring in the pipeline, due to the inconsistent production and measurement direction of the probes. In this study, a small directional measuring probe was designed for the soil profile moisture non-contact sensor using the principle of Standing Wave Rate (SWR), electromagnetic simulation, and printed circuit board technology. Then, the impedance conversion circuit of the probe was designed to meet the requirements of SWR measurement. A vector network analyzer was utilized to determine the relationship among the probe measurement, medium, and conductivity. In detail, firstly, the impedance characteristics of the probe structure were verified to simulate the High-Frequency Structure Simulator (HFSS) electromagnetic field. The optimal probe size was then determined as the radius 15 mm and height 20 mm, according to the impedance and standing wave ratio of the probe at different heights and radii. The impedance of the probe was transformed in the impedance circuit, further to determine the relationship between the probe impedance and the object to be measured under different conductivity, as well as the dielectric constant. Secondly, the appropriate impedance conversion circuit of the probe was designed to verify in the range suitable for SWR to detect soil moisture using a vector network analyzer. Thirdly, a series of tests were performed on the different dielectric constants to evaluate the measurement accuracy of the probe. The measuring range of the probe was an approximate cylinder with a height of 15 mm and a radius of 37 mm, according to the impedance characteristics of the soil moisture sensor in the profile. Finally, the soil samples with multiple moisture and conductivity gradients were configured to evaluate the probe impedance. The results showed that, when the soil conductivity was less than 6 300 μS/cm in the range of soil moisture content 3%-56%, that was, in non saline alali soil, the relative error of the maximum soil volume moisture content of the sensor was 6.33% affected by soil conductivity. Consequently, the maximum error of the sensor was reduced by 0.17-5.27 percentage points in the non saline soil, where the electrical conductivity was in the range of 0-6 300 μS/cm, compared with the commonly-used ET-5 and 5TE sensors in the foreign market. As such, this new sensor can fully meet the needs of actual detection in the field. Therefore, the finding can provide new theoretical and technical support for the localization of profile soil moisture sensors. [ABSTRACT FROM AUTHOR]

Dynamically-tunable impedance matching is a key feature in numerous radio-frequency (RF) applications at high frequencies (10 s of MHz) and power levels (100s-1000 s of Watts and above). This work develops techniques that enable the design of high power tunable matching networks (TMN) that can be tuned orders of magnitude faster than with conventional tunable impedance matching techniques, while realizing the high power levels required for many industrial applications. This is achieved by leveraging an emerging technique - known as phase-switched impedance modulation (PSIM), which involves switching passive elements at the rf operating frequency - that has previously been demonstrated at rf frequencies at up to a few hundred Watts. In this paper, we develop design approaches that enable it to be practically used at up to many kilowatts of power at frequencies in the 10 s of MHz. A detailed analysis of the factors affecting the losses as well as the tradeoffs of a basic PSIM-based element is provided. Furthermore, it is shown how incorporating additional stages to the PSIM-based element, including impedance scaling and / or the addition of series or shunt passive elements, influences the losses and enables the efficient processing of high power levels given the limitations of available switches. A PSIM-based TMN that matches load impedances to 50Ω and delivers up to 1.5 kW of power at frequencies centered around 13.56 MHz is implemented and tested over a load impedance range suitable for various industrial plasma processes.

DQ impedance-based method has been widely used to study the stability of three-phase converter systems. As the dq impedance model of each converter depends on its local dq reference frame, the dq impedance modeling of complex converter networks gets complicated. Because the reference frames of different converters might not fully align, depending on the structure. Thus, in order to find an accurate impedance model of a complex network for stability analysis, converting the impedances of different converters into a common reference frame is required. This paper presents a comprehensive investigation on the transformation of dq impedances to a common reference frame in complex converter networks. Four different methods are introduced and analyzed in a systematic way. Moreover, a rigorous comparison among these approaches is carried out, where the method with the simplest transformation procedure is finally suggested for the modeling of complex converter networks. The performed analysis is verified by injecting two independent small-signal perturbations into the d and the q axis, and doing a point-by-point impedance measurement.

This brief presents a new design methodology of single-chip reconfigurable CMOS RF power amplifier (PA) supporting both dual-band and multi-power-mode operation. The proposed architecture utilizes a novel switched-capacitor based output network to facilitate differential signal combining and impedance transformation at two widely separated frequency bands. It can offer three distinct output power levels (saturation) to be selected for multi-power-mode applications. Besides, closed-form explicit equations are readily available for the evaluation of component values. For verification, a PA operating at 1.8/2.6 GHz (non-concurrent), with three distinct saturation power levels (21, 23, 26 dBm) and peak efficiency of about 30%, is designed and fabricated using $0.35~{\mu }\text{m}$ CMOS process. [ABSTRACT FROM AUTHOR]

A novel design method of microstrip diplexer without extra matching circuit is proposed in this paper. Because of the synthesizable circuit parameters and controllable transmission zeros (TZs) in composite resonator (CR) cell, diplexer A based on CR cell is proposed. By allocating TZs at center frequency of the opposite channel, as well as the using of impedance transformations of J inverters, high isolation and good passband selectivity are realized in diplexer A without extra matching circuit. In order to improve the stopband performance, diplexer B based on coupled CR cells is proposed. Furthermore, diplexer B using the proposed design method is implemented by directly combining two bandpass filters (BPFs), which simplifies significantly the design process of diplexers. Diplexer A operated at 1/1.2 GHz and diplexer B operated at 1/1.5 GHz are designed and fabricated. The measured isolation characteristics in diplexer A and diplexer B are all higher than 40 dB. Good agreements between simulated and measured results are achieved, which successfully verifies the proposed design method of diplexers.

In this paper, the systematic design for a dual-band balun featuring impedance transformation and high output isolation is presented. A dual-band balun capable of conducting transformation between an unbalanced 50-$\Omega $ line and a balanced one of 300-$\Omega $ is proposed for its operations at 2.4/5.2 GHz with high output isolation. The combination of a dual-band $\lambda $ /4 stepped-impedance-stub line and a dual-band $3\lambda $ /4 T-junction coupled line produces an output phase difference of 180° at the two operating frequencies for the balun. An important feature of the proposed design is the 1:6 impedance transformation from an unbalanced source to a balanced load. High isolation can also be achieved by introducing an isolation circuit between the output ports. The measured isolation is better than -26 dB. The phase imbalance is under 3°, and the magnitude imbalance is less than 0.9 dB within the bandwidths.

In this study, a parallel-segmented complementary metal-oxide–semiconductor (CMOS) step-up autotransformer was developed to improve the impedance transformation ratio. In addition, a corresponding scalable segmentation-based model was developed on a CMOS case. The proposed segmentation-based model was used to predict the accurate performance of a parallel-segmented autotransformer. The parallel-segmented step-up autotransformer was fabricated through a standard 65 nm CMOS process. The modeled results showed good agreement with the measured results. The implemented one/two parallel-segmented CMOS step-up autotransformer changed the impedance from 50 Ω to 9.5 Ω/6.1 Ω with −1.21 dB/−1.54 dB minimum insertion loss at 3 GHz. [ABSTRACT FROM AUTHOR]

In this brief, a novel balanced filter named impedance-transforming differential bandpass filter (ITDBPF) is proposed, which is the first differential device to realize both wideband impedance transformation and bandpass filtering simultaneously. A core block consisting of cascaded transmission lines and parallel stubs forms this presented circuit with two additional open stubs. Under differential-mode excitation, the transfer function of the equivalent circuit is the same as the one of Chebyshev, and the filtering characteristics are obtained corresponding to the specified filtering parameters. The open stubs increase multiple transmission zeros under common-mode excitation to greatly broaden the bandwidth of common-mode rejection. To verify the proposed theory, a wideband balanced filter centered at 2 GHz with a theoretical 3-dB bandwidth of 72% is designed and measured to prove the correctness of the design theory. [ABSTRACT FROM AUTHOR]

Feeding network with complex weight has important prospect in various applications. In this article, the design of complex weighted feeding network based on generalized coupled-resonator filter theory is proposed. To design the power and phase distribution all-in-one, a novel type of multifunctional generalized filter is proposed. It has abilities of impedance transformation, phase shift, and filtering. Then, the design method of the network with arbitrary power distribution and arbitrary phase distribution by this generalized filter is demonstrated. Four different design examples are executed to validate the proposed theory. This proposed network overcomes many shortages of these existing methods and possesses several additional advantages, such as simple structure, designable bandwidth, and filtering function. [ABSTRACT FROM AUTHOR]

In this article, the co-design of novel self-packaged balanced bandpass filters (BPFs) integrated with the functionality of impedance transformation is presented for the first time. The proposed design is based on a modified branch-line structure, which is composed of two different branch lines and two identical coupled-line sections. Analysis results show that the considered filters can not only achieve Chebyshev equal-ripple responses with impedance transformation properties for the differential mode (DM) but also can efficiently improve the bandwidth of the common-mode (CM) rejection with resorting to this modified branch-line structure. Furthermore, according to the specified equal-ripple fractional bandwidth (FBW), in-band return loss (RL) level, and impedance transformation ratio ${m}$ , the DM frequency response can be directly determined. Two design prototypes, the second-order balanced BPF with a 50–75- $\Omega $ ($m= 1.5$) impedance transformation and the third-order one with a 50–200- $\Omega $ ($m= 4$) impedance transformation, are implemented in self-packaged forms by using the multilayer liquid crystal polymer (LCP)-bonded printed circuit board (PCB) technology. Theoretical, simulated, and measured results are recorded in good agreement, well verifying the design concept. [ABSTRACT FROM AUTHOR]

In this paper, a new self-packaged wideband balun with the high selective bandpass filtering response and impedance transformation characteristic is presented. By virtue of circuit transformations, corresponding two-port equivalent circuit with asymmetrical port impedances is put forward. The analysis results of this two-port network exhibit that the proposed new design is able to achieve a quasi-elliptic equal-ripple response with three transmission poles and four transmission zeros. In addition, the frequency response can be directly determined according to the desired design specifications of impedance transformation ratio k, ripple fractional bandwidth (FBW), and in-band return loss RL. For validation purposes, a demonstrated wideband balun bandpass filter (BPF) working at 2.0 GHz with 50–100- $\Omega $ impedance transformation has been implemented by utilizing the multilayer liquid-crystal polymer (LCP) bonded printed circuit board (PCB) lamination technology. Theoretical, simulated, and measured results are recorded in good agreement, well verifying the design method. [ABSTRACT FROM AUTHOR]

This paper presents an automatic impedance transforming technique to extend the radio frequency rectifier input power range with high conversion efficiency. The rectifier employs two branches of subrectifier, each achieving impedance matching at high and low input power ranges. Then, the two branches are connected by a $\lambda/4 $ T-junction power divider. With such configuration, the input impedance of the two subrectifiers are transformed automatically, allowing the impedance matching over a wide input power range. In this way, the injected power can be optimally delivered to the subrectifiers, achieving a high efficiency over this wide input power range. This scheme manages to eliminate the power detetor for branch selection and can be applied to both single- and dual-band rectifiers with a reduced design difficulty. For validation, a single-band rectifier working at 915 MHz and a dual-band rectifier at 915/2450 MHz are implemented. Design analysis on the single- and dual-band rectifiers is carried out. The measurement results show that 68% maximum efficiency is achieved for the single-band (915 MHz) rectifier, and the input power range for the efficiency >70% of the peak efficiency is from −5 to 31 dBm. Besides, the dual-band rectifier shows 66% and 58% peak efficiencies at 915 and 2450 MHz, respectively. The input power range is from −6 to 33 dBm for the efficiency >70% of its peak value at 915 MHz, while from 10 to 32 dBm at 2450 MHz. These indicate that the input power range with high efficiency is extended. [ABSTRACT FROM AUTHOR]

For large power application of inductively coupled power transfer (ICPT) system, such as traffic railway, multiple pickups have to be adopted. The condition exists that current unbalance of ICPT system with multiple parallel pickup modules, which will cause instability and low reliability. Aimed to solve the issue, the paper analyses the uncoupled module of ICPT system, assesses the impact of the mutual inductance, compensated state, and coil resistance on current unbalance, and put forward a novel current-balance strategy to balance the parallel currents by introducing the circuit of impedance transformation including semi-controlled rectifier, and BUCK, and BOOST circuits. Experiments have been done on the platform of ICPT prototype, and the experimental results are presented to show the correctness of the theoretical analysis and the effectiveness of the control strategy. When the output voltage is 220 V and load is 6 Ω, the output power is 8 kW. The amplitude ratio of the two parallel currents is 2.04 without control, and the amplitude of the two current is almost equal when adopting the strategy. System efficiency stays constant or increases slightly after adopting the proposed control strategy. [ABSTRACT FROM AUTHOR]

This work presents a 1X4 fully reconfigurable power divider with a wide range of power divisions and reduced size, designed for adaptive null forming and beam steering networks in RF front ends. The design is based on the impedance transformation of series-coupled cascaded transmission lines and a reconfigurable isolation network. The impedance of power-dividing arms is transformed by tuning the voltage-dependent equivalent capacitor, controlling insertion loss, and indirectly influencing the power division ratio. Four transmission states with sixteen different power levels are realized. This design approach is validated by fabricating a prototype with four output ports. The measured power division varies from 6.5 dB to 18 dB at the center frequency, and the return loss is greater than -32 dB. Output port isolation is greater than -30 dB, and the phase response at output ports only shows a difference of less than 2 degrees. The power at any output port can be reconfigured independently without affecting the system's overall performance, achieved through a series-coupled transmission line, contributing to a reduction in size. A size reduction of 37 percent is attained in this design. The proposed power divider can provide a wide range of power levels at all output ports within a narrow band around the center frequency. Hence, the design is suitable for beam steering networks, pattern, and polarization reconfigurable antenna arrays. The design also has extension capability into N-way configurations. [ABSTRACT FROM AUTHOR]

This paper proposes a novel planar dual-band coupled-line balun with impedance transformation and high isolation. Closed-form design equations are obtained based on the classical even-odd mode equivalent approach. For convenience of designing and synthesizing such a novel dual-band balun, the practical ranges of the frequency ratio, terminated impedances, and two free variables are provided under the conventional microstrip fabrication constraints. By adopting four coupled-line sections, six transmission-line stubs, and an isolation resistor, a microstrip prototype balun working at 1.0/2.6 GHz is designed, fabricated, and measured. There is a good agreement between the simulated and measured results. The wide bandwidths of 290 MHz from 0.83 to 1.12 GHz and 270 MHz from 2.44 to 2.71 GHz are obtained with the measured return losses (|S11|, |S22|, |S33|) and the isolation (|S23|) better than 10 dB, which effectively confirm the proposed theoretical predictions.

There is an established equivalence between Huygens’ metasurfaces and lattice networks. This paper proposes an extension to this equivalence for bianisotropic Huygens’ metasurfaces, where bianisotropy refers to the magnetoelectric coupling between the effective electric and magnetic responses. A modified version of the lattice network is proposed that exhibits a one-to-one mapping to the bianisotropic sheet transition conditions by incorporating ideal transformers. A possible realization of bianisotropic Huygens’ unit cells is also proposed that relies on offsetting the wire with respect to the loop in the wire/loop topology. This is followed by deriving analytical expressions for the image impedances and the corresponding transfer function of bianisotropic Huygens’ metasurfaces. Inverse analytical expressions are also derived that govern the required effective electric and magnetic responses and the magnetoelectric coupling for achieving wideband electrical transparency (symmetric case) and wideband impedance transformation (bianisotropic case) with these Huygens’ metasurface unit cells. Moreover, it is shown that these expressions can be realized with transmission-line stubs. These expressions are then used to design subwavelength thin Huygens’ metasurfaces immersed in an air gap between two dielectric media. It is shown, through full-wave simulations, that wideband electrical transparency and impedance transformation are realized for a normally impinging plane wave. [ABSTRACT FROM AUTHOR]

In this paper, an adaptive N-path filter design technique is presented. The filter designed by this method can be reconfigured to different shapes, e.g., Butterworth or Chebyshev with variable bandwidth (BW), based on the user requirements. In addition, an analytical synthesis procedure is introduced to realize high-order bandpass filters (BPFs) based on N-path architecture with a prescribed set of specifications. A proof-of-concept BPF is fabricated and measured in a 65-nm CMOS process. The filter can be reconfigured to realize different filter shapes by changing coupling capacitors. The BW of the proposed filter is also tunable. The passband of the filter is tunable from 0.2 to 1.2 GHz with a gain of 14.5–18 dB, a noise figure of 3.7–5.5 dB, and a total power consumption of 37.5–52.7 mW. The channel BW can be varied from 20 to 40 MHz and the filter out-of-band third-order intercept point ( $\Delta f=50$ MHz) is 25 dBm. [ABSTRACT FROM AUTHOR]

Plasma generation systems represent a particularly challenging load for radio-frequency power amplifiers owing to the combination of high operating frequency (e.g., 13.56 MHz) and highly variable load parameters. We introduce a dynamic matching system for inductively coupled plasma (ICP) generation that losslessly maintains near-constant driving point impedance (for low reflected power) across the entire plasma operating range. This new system utilizes a resistance compression network (RCN), an impedance transformation stage, and a specially configured set of plasma drive coils to achieve rapid adjustment to plasma load variations. As compared to conventional matching techniques for plasma systems, the proposed approach has the benefit of relatively low cost and fast response, and does not require any moving components. We describe suitable coil geometries for the proposed system, and treat the design of the RCN and matching stages, including design options and tradeoffs. A prototype system is implemented and its operation is demonstrated with low pressure ICP discharges with O2 , C4F 8, and SF $_{{6}}$ gases at 13.56 MHz and over the entire plasma operating range of up to 250 W. [ABSTRACT FROM AUTHOR]

ABSTRACT A wideband two-way Gysel power divider/combiner is presented based on a modified Marchand balun. With a −15 dB input and output return loss criteria, proposed method has a bandwidth of about 53%, while dimensions are still similar to the conventional Gysel power divider/combiner. The structure of the designed planar microstrip in-phase power divider is fairly simple, practical, and easily fabricated without requiring complex multiple metal or dielectric layers. In addition to CAD simulation and optimizations, with the aid of even- and odd-mode analysis, a mathematical designing framework is also established. To verify the design approach, the proposed divider/combiner is fabricated and measured at the S-band of frequency. There is a good agreement between simulation and experimental results. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:949-955, 2017 [ABSTRACT FROM AUTHOR]

A planar microstrip circuit is proposed in this article to design a dual-band balanced-to-unbalanced out-of-phase power divider with inherent impedance transformation. This balanced-to-unbalanced power divider, which essentially consists of two pairs of cascaded coupled lines, two dual-band 90° phase shifters, and a grounded resistor, features the dual-band application with inherent impedance transformation, the equal power division with out of phase, high isolation between two outputs, good ports (A, 3, and 4) matching, and high common-mode noise suppression as well as the excellent conversion inhibition between the differential-mode signals and the common-mode noise. The closed-form solutions are obtained by using the traditional odd- and even-mode analytical methods. Finally, a practical microstrip balanced-to-unbalanced power divider, which operates at 0.9 GHz and 1.8 GHz, is designed and fabricated. The simulated and measured results verify the correctness of the circuit and the design theory. [ABSTRACT FROM PUBLISHER]

The authors propose a method for computation of electrical parameters of single pole multi-throw (SPMT) switch, the input matching of which is provided by the transmission line transformer, located on its input. The influence of parameters of line segments, which connect the lines branching outputs and keys in each path, on the value of SPMT switch operating parameters are offered. Use of the proposed method is demonstrated by the way of example of design and simulation of SPDT and SP4T switches with different types of keys.

A novel dual-band out-of-phase power divider with inherent impedance transformation and high power-handling capability is presented in this article. This proposed power divider essentially consists of four sections of double-sided parallel striplines for the signal transmission, an inserted middle conductor plane as the common ground, and two resistors to improve the isolation between two outputs. Closed-form design equations are derived based on the conventional even- and odd-mode analytical methods and the transmission-line theory. Finally, a practical three-layer out-of-phase power divider is designed and fabricated. The experimental results show that good ports matching, excellent isolation between two outputs, and out-of-phase performance are simultaneously achieved at both 1 and 2.6 GHz. [ABSTRACT FROM AUTHOR]

A compact coupled-line circuit is proposed in this article to design a kind of dual-band Gysel power divider (Gysel, 1975). This circuit inherently consists of three pairs of coupled lines, an open stub, two output extension lines, and two grounded isolation resistors. Besides the high power-handling capability, this Gysel power divider features dual-band operating performance, wide frequency ratios, flexible impedance transformation, etc. Using the transmission-line theory and rigorous even- and odd-mode analysis, closed-form solutions for the electrical parameters are obtained. A practical Gysel power divider, which works at 0.92 and 2.45 GHz, simultaneously, is designed and fabricated for radio frequency identification application. Good agreement between the simulated and measured results verify the correctness of the design theory. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerator (TENG) is a new high-efficiency electromechanical conversion mode proposed in recent years. When triboelectric nanogenerator is used as sensor, like other types of sensors, it can use current signal as sensing signal, but it outputs weak current signal with high impedance, which is not conducive to direct application. In this paper, a preprocessing method for weak current signal is proposed. The I/V conversion measurement method and the direct measurement method are theoretically analyzed, and the principle of parameter selection of circuit components is provided respectively. After that, the experiment of Contact Separated Triboelectric Nanogenerator (CS-TENG) is used to verify that the proposed I/V conversion measurement method has higher accuracy than the direct measurement method, and then the Rotary Triboelectric Nanogenerator (R-TENG) and the single electrode triboelectric nanogenerator (S-TENG) are used further verifies the design theory of the I/V conversion measurement method. Finally, it is concluded that the I/V conversion measurement method can convert the high impedance weak current signal output by TENG into a low impedance low voltage signal. Through reasonable component parameter selection, the measurement error can be controlled within 6 %, which can not only be used in current signal extraction of TENG, but also be expected to be used for current signal characterization in TENG when TENG is used as an energy harvester. An I/V conversion measurement method on the output current signal of the TENG sensor is proposed, which converts the high-impedance weak current signal output by the TENG sensor into a low-impedance and low-voltage signal, which can achieve more accurate current signal measurement. The current measurement scheme can completely restore the current change waveform output by the TENG sensor with small errors, which improves the portability and practicability of the TENG sensor. At the same time, this provides a new method for the extraction of the current signal of the TENG sensor, and can also be applied to the current signal characterization of the TENG when it used as an energy harvester. [Display omitted] • The proposed method can accurately sense the current signal of the TENG sensor with high accuracy and low cost. • The proposed method can be used as a universal approach for extracting the current signals for different kinds of TENG sensor. • The proposed method is expected to be applied to the characterization of current signal in TENG when it used as an energy harvester. [ABSTRACT FROM AUTHOR]

An impedance-transforming coupled-line Wilkinson power divider with port isolations and extensions is proposed in this article. It is composed of a coupled line section, an isolation resistor, and three extended transmission lines at each port for physical isolation and convenient installation. By substituting additional transmission lines for the three port extensions and introducing coupled lines, the power divider achieves suppressed insertion loss with enhanced physical output isolation. Closed-form design equations are successfully derived and verified. The excellent agreement between simulated and measured results shows that the proposed power divider can realize required functions with good matching, low insertion loss, fine isolation, and wide bandwidth. [ABSTRACT FROM PUBLISHER]

ABSTRACT This article presents a reconfigurable monolithic step-up autotransformer. In addition, its reconfigurable operation has been analyzed using a proposed nonideal transformer model. A corresponding complete model for a reconfigurable autotransformer has also been developed on a silicon substrate case. The proposed reconfigurable autotransformer was fabricated using a standard 65-nm CMOS process. The measurement results demonstrate that the fitted curves using the proposed complete model agree well with the measured results. The proposed reconfigurable autotransformer can perform the required impedance changes depending on the power amplifier output power change with low insertion loss. The 50-Ω load impedance is transformed to a low value of 3.28 Ω in high power (HP) mode operation, and it is transformed to a high value of 12.26 Ω in low power (LP) mode operation at 0.9 GHz. The transformer insertion losses in HP and LP mode operations are −1.424 dB and −0.706 dB at 0.9 GHz, respectively. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1662-1666, 2015 [ABSTRACT FROM AUTHOR]

In this paper, we propose a design method of multi-way combining networks with impedance transformation for millimeter-wave (MMW) power amplifiers (PAs) to achieve high output power and wideband performance simultaneously in millimeter-wave frequency. Based on the proposed methodology, three power amplifiers are designed and fabricated in V-band, W-band, and D-band using 65-nm CMOS technology. With 1.2-V supply, the saturation powers of these power amplifiers are 23.2 dBm, 18 dBm and 13.2 dBm at 64 GHz, 90 GHz, and 140 GHz, with 25.1-GHz, 26-GHz, and 30-GHz 3-dB bandwidth, respectively. Compared with the published MMW amplifiers, these PAs achieve high output power and wide band performances simultaneously, and the ouput power levels is the state-of-the-art performance at these frequencies. [ABSTRACT FROM AUTHOR]

A widely tunable 4th order BPF based on the subtraction of two 2nd order 4-path passive-mixer filters with slightly different center frequencies is proposed. The center frequency of each 4-path filter is slightly shifted relative to its clock frequency (one upward and the other one downward) by a g_m-C technique. Capacitive splitting of the input signal is used to reduce the mutual loading of the two 4-path BPFs and increase their quality factors. The filter is tunable from 0.4 GHz to 1.2 GHz with approximately constant bandwidth of 21 MHz. The in-band 1-dB compression point of the filter is -4.4 dBm while the in-band IIP_3 of the filter is +9 dBm and the out-of-band IIP_3 is +29 dBm (\Delta f=+50 MHz). The ultimate rejection of the filter is > 55 dB and the NF of the filter is 10 dB. The static and dynamic current consumption of the filter are 2.8 mA from 2.5 V and 12 mA from 1.2 V, respectively (at 1 GHz). The LO leakage power to the input port is < -60 dBm. The filter has been fabricated in CMOS LP 65 nm technology and the active area is 0.127 mm^2. [ABSTRACT FROM PUBLISHER]