Impedance Matching Network Research Articles

Polarization-Resolved THz Imaging With Orthogonal Heterostructure Backward Diode Detectors

A fully integrated lens-coupled dual-polarization detector for imaging was designed, fabricated, and characterized in the terahertz (THz) region. Two zero-bias heterostructure backward diodes (HBDs) were monolithically integrated into a planar dual-polarization annular-slot antenna. An impedance matching network consisting of an interdigitated DC block and shorted stubs was implemented for maximum power transfer. The fabricated chip was then mounted on an extended hemispherical silicon lens for high antenna efficiency. The performance of the integrated detector has been characterized at 200 GHz. The detector module can simultaneously measure the two orthogonal linear polarized components of the incident THz waves, and hence obtain the polarization direction. On the basis of this polarimetric detection, polarization-resolved imaging of a Gaussian beam, as well as birefringent samples, was performed using the integrated detectors. The angular resolution of the polarization detection has been demonstrated to be as small as 3°. The single-pixel detector demonstrated here is amenable to array applications for THz focal-plane arrays that will have a significant impact on a wide range of remote sensing, though-barrier imaging, and detection/identification applications.

Customizable and upgradable design triple-band dual circular polarization rectenna for ambient RF energy harvesting

A Customizable and upgradable design of triple-band dual circular polarization (CP) rectenna is presented for ambient RF energy harvesting of available frequency bands (i.e., 1800, 2.15, 2.42) efficiently. A broadband dual CP receiving antenna is proposed with a broadband impedance matching bandwidth of 123% from 1 to 4.2 GHZ and axial-ratio (AR) bandwidth of 75% from 1.45 to 3.06 GHz with a maximum gain of 5.54 dBi to cover the selected frequency bands. Besides, the proposed triple-band rectifier with a multi-stub impedance matching network is feasible for RF harvesting with the new design method, and the non-dependence of the resonance frequencies on the distance between the stubs, the rectifier can be easily adjusted for other frequencies. The proposed rectenna’s measurement results show that the generated average dc output voltage and conversion efficiency are improved to 0.8 V and 60%, respectively, at a low RF input power density of −2 dBm for a load resistance of 1.5 kΩ.

A Compact D-Band CMOS Frequency Sixtupler Using a Mode Analysis of the Harmonics

A miniaturized D-band frequency sixtupler using a mode analysis of the harmonics is proposed to improve the output power of the CMOS process using a low driving signal. The operation mode of the harmonics in a differential frequency multiplier is analyzed to independently control the behavior at odd- and even-order harmonics. The proposed CMOS sixtupler consists of a tripler, a buffer amplifier, a push–push doubler, and impedance matching networks. The interstage network between the tripler and the buffer amplifier performs impedance matching of the desired frequency and filtering of unwanted signals. The network between the buffer and the doubler simultaneously performs impedance matching while acting as the harmonic reflector. The output power of the doubler located at the final stage of the sixtupler is improved by LC source degeneration, providing LC resonance, and a high impedance condition at the second-harmonic frequency. The proposed sixtupler was implemented in an area of 0.4 mm2 using the 65-nm CMOS technology. The measurement results indicate a saturated power of −1.2 dBm with a harmonic rejection ratio (HRR) of 25 dBc for an input driving power of 15.5 dBm at 148.2 GHz. The maximum conversion gain (CG) is −0.7 dB at a low driving power of −6.5 dBm at 150.6 GHz.

A Novel Impedance Matching Network Suitable for Designing High-Efficiency Power Amplifiers

In this paper, a novel impedance matching network (IMN) for designing high-efficiency power amplifiers (PAs) is presented. With this method, the fundamental matching network (FMN) and the harmonic control network (HCN) are incorporated into a single network, which is composed of a λ/8 (λ is wavelength) transmission-line (TL) and a λ/4 TL. Based on it, the design procedure is more straightforward. Besides, the forbidden regions and feasible regions of the proposed network at the first three harmonics are also analyzed. The results show that the forbidden regions are very small. Finally, as an example, a harmonic tuned (HT) PA is designed and implemented using a GaN HEMT transistor. The measured results demonstrated that the fabricated HT PA working at 3.0 GHz delivers a power-added efficiency (PAE) of 79.2%, a gain of 11.6 dB and an output power (Pout) of 41.0 dBm.

Circuit-level design principles for transmission-mode microwave impedance microscopy

A recently developed technique of transmission-mode microwave impedance microscopy (T-MIM) has greatly extended the capabilities of standard reflection-mode MIM to novel applications, such as the in operando study of nanoscale electro-acoustic devices. As is common for new techniques, systematic design principles for boosting sensitivity and balancing bandwidth are lacking. Here, we show numerically and analytically that the T-MIM signal is proportional to the reflection-mode voltage enhancement factor η of the circuit, as long as the output impedance of the local voltage source is properly treated. We show that this proportionality holds in the currently achievable “weak sampling” regime and beyond, for which we demonstrate a realistic path with commercially available superconducting components and critically coupled impedance matching networks. We demonstrate that for these next-generation designs, the sensitivity is generally maximized at a slightly different frequency from the unloaded S11 resonance, which can be explained by the maximum power transfer theorem.

Adaptive Impedance Matching Network for Contactless Power and Data Transfer in E-Textiles.

One of the major challenges associated with e-textiles is the connection between flexible fabric-integrated wires and rigid electronics. This work aims to increase the user experience and mechanical reliability of these connections by foregoing conventional galvanic connections in favor of inductively coupled coils. The new design allows for some movement between the electronics and the wires, and it relieves the mechanical strain. Two pairs of coupled coils continuously transmit power and bidirectional data across two air gaps of a few millimeters. A detailed analysis of this double inductive link and associated compensation network is presented, and the sensitivity of the network to changing conditions is explored. A proof of principle is built that demonstrates the system's ability to self-tune based on the current-voltage phase relation. A demonstration combining 8.5 kbit/s of data transfer with a power output of 62 mW DC is presented, and the hardware is shown to support data rates of up to 240 kbit/s. This is a significant improvement of the performance of previously presented designs.

Suppression of Common-Mode Resonance in Multiband Base Station Antennas

5G demands a significant increment in the number of connected devices. As a result, gNodeBs are constantly pushed to serve more spectrum and smaller sectors. These increased capacity demands are met by using multiband antennas in base stations. One of the key challenges with multiband antennas is the pattern distortions due to the presence of other surrounding antenna element structures. This work provides a novel approach to address the challenge of pattern distortion in the lower frequency band 690-960 MHz due to common-mode (CM) currents in the high- frequency-band antenna element operating in the 1810-2690 MHz band. A common-mode suppression circuit is integrated with the impedance matching network of the high-band antenna element to reduce these common-mode currents. The experimental results verified that the common-mode suppression circuit reduces the common-mode currents at low-band frequencies by moving the common-mode resonance frequency outside the low frequency band, resulting in cleaner low-band patterns meeting pattern specifications.

24–35 GHz Filtering LNA and Filtering Switch Using Compact Mixed Magnetic-Electric Coupling Circuit in 28-nm Bulk CMOS

This paper presents compact 24–35 GHz filtering low noise amplifier (LNA) and filtering switch in 28-nm CMOS technology. A compact mixed magnetic-electric coupling circuit is designed, where a transmission zero is introduced out of the passband due to the cancellation of the magnetic and electric couplings. By analyzing the impedance characteristics, this structure can be designed with the impedance conversion function to replace the widely used transformers in integrated circuit designs. It shows the advantages of easy control of coupling coefficient and out-of-band rejection. Then, an LNA employing the magnetic-electric coupling circuits as impedance matching networks is designed. Image rejection can be achieved without increasing the circuit area. Moreover, by loading transistors to this mixed magnetic-electric coupling circuit, the input impedance can be controlled by the parasitic components of the transistor. Subsequently, a filter passband can be switched on and off, realizing a very compact filtering single-pole single-throw (SPST) switch. The fabricated filtering LNA is measured with a 3-dB bandwidth of 24–35 GHz, a noise figure (NF) of 2.4-3.6 dB, a maximum gain of 22 dB, and suppression of better than 25 dBc below 18 GHz. The filtering switch shows a minimum on-state loss of 2.1 dB at 28.6 GHz with better than 12.9 dB rejection below 16 GHz and off-state isolation of higher than 19 dB.

Compact Filtering Balun-Diplexer Using Coupled-Line-Loaded Hairpin Ring Resonator

A filtering balun-diplexer (FBD) with compact size and high channel isolation is proposed based on the dual-mode coupled-line-loaded hairpin ring resonator (C-HRR). The special features of C-HRR are presented and concluded. The out-of-phase current distribution of the C-HRR at the odd-mode resonant frequency is noticed and utilized in the balun design. By carefully arranging the resonant frequencies and coupling topology, the two channels of the FBD can share one common C-HRR to reduce the circuit size. The lower and higher channel filtering baluns are designed separately and integrated directly into the FBD without extra impedance matching network because of the low loading effect. For validation, an FBD is fabricated with circuit size of 0.24 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\lambda }_{\mathrm{ g}}\,\, {\times }\,\,0.14{\lambda }_{\mathrm{ g}}$ </tex-math></inline-formula> , where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\lambda }_{\mathrm{ g}}$ </tex-math></inline-formula> is the guide wavelength at the center frequency of the lower passband. The isolation between the lower and higher channels is greater than 39 dB with the common mode rejection better than 34 dB over the passbands.

A Wide-Bandwidth PVT-Reconfigurable CMOS Power Amplifier with an Integrated Tunable-Output Impedance Matching Network

This paper proposes a wideband CMOS power amplifier (PA) with integrated digitally assisted wideband pre-distorter (DAWPD) and a transformer-integrated tunable-output impedance matching network. As a continuation of our previous research, which focused only on linearization tuning for wideband and PVT, this work emphasized improving the maximum output power, gain and PAE across the PVT variations while maintaining the linearity for a wide frequency bandwidth of 1 GHz. The DAWPD is employed at the driver stage to realize a pre-distorting characteristic for wideband linearization. The addition of the tunable-output impedance matching technique in this work provides stable output power, PAE and gain across the PVT variations, through which it improves the design's robustness, reliability and production yield. Fabricated in CMOS 130 nm with an 8-metal-layer process, the DAWPD-PA with tunable-output impedance matching can achieve an operating frequency bandwidth of 1 GHz from 1.7 to 2.7 GHz. The DAWPD-PA attained a maximum output power of 27 to 28 dBm with a peak PAE of 38.8 to 41.3%. The power gain achieved was 26.9 to 29.7 dB across the targeted frequencies. In addition, when measured with a 20 MHz LTE modulated signal, the DAWPD-PA achieved a linear output power and PAE of 24.0 to 25.1 dBm and 34.5 to 38.8% across the frequency, respectively. On top of that, in this study, the DAWPD-PA is proven to be resilient to process-voltage-temperature (PVT) variations, where it achieves stable performances via the utilization of the proposed tuning mechanisms, mainly contributed by the proposed transformer-integrated tunable-output impedance matching network.

Impedance Matching Network of Passive Coupler with Coaxial Cable for Airborne Sonar Applications

A design methodology is proposed to implement an impedance-matching network in a high-power underwater acoustic transmitting system to minimize power loss through long cables. For this, a Lumped-parameter electrical equivalent circuit model has been developed to analyze the transmitting system along with various couplers and de-couplers introduced for simultaneous transmission of data and DC power along with high-power AC. The effects of these couplers on the end performance of the system have been studied and compensated for by suitably modifying the impedance matching lines (ML). The appropriate impedance matching lines significantly enhance the power by about 300 watts and improve the power factor to 100 %.

Broadband Doherty Power Amplifier Using Short Ended λ/4 Transmission Lines Based on the Analysis of Negative Characteristic Impedance

This paper presents a broadband Doherty power amplifier (DPA) using quarter-wavelength ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda $ </tex-math></inline-formula> /4) transmission lines with negative characteristic impedance. In conventional DPA designs, the load modulation network is frequency-dependent, leading to bandwidth limitation at the back-off power region. In this design, by integrating two <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda $ </tex-math></inline-formula> /4 transmission lines with negative characteristic impedance into the main and auxiliary branches, the impedance at the back-off power can be manipulated to maintain high efficiency at back-off power over a wide frequency range. Thus, the operational bandwidth is extended. In circuit realization, the two negative characteristic impedance <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda $ </tex-math></inline-formula> /4 transmission lines are replaced by paralleled negative LC components. Then, the negative capacitor is combined into the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pi $ </tex-math></inline-formula> -shaped impedance matching network, while the negative inductor is eliminated by introducing Norton transformation. For verification, a broadband DPA with a fractional bandwidth of 108.6% from 0.8 to 2.7 GHz is implemented. The measured saturated output power is 41.8-44 dBm. The saturated and 6-dB back-off power drain efficiencies are 47.6%-84.4% and 39.5%- 52%, respectively. A 20-MHz LTE modulated signal with peak-to- average power ratio (PAPR) of 7.5 dB is also applied to measure the fabricated DPA. After digital predistortion, the adjacent channel leakage ratio (ACLR) better than −45.35 dBc is achieved, and the measured average efficiency is higher than 40% within the operating band.

High-Performance Multiband Ambient RF Energy Harvesting Front-End System for Sustainable IoT Applications—A Review

The increasing demand for wireless Internet of Things (IoT) calls for power efficient RF energy harvesting approach. The current dominant single-band RF energy harvesting front-end system restricts itself to a single frequency, which is at the risk of ineffective operation when the harvesting frequency is unavailable. This paper reviews and explores the alternative approach of a multiband RF energy-harvesting front-end system. It covers all essential circuitry of a multiband RF energy harvesting front-end system, starting from the recent RF surveys which investigate the typical, usable, and high-strength RF input, to the overview of the state-of-the-art antenna, impedance matching network (IMN), and RF-DC rectifier. The recent advancement of the multiple RF input harvesting abilities, reflection loss minimization, and performance improvement are comprehensively reviewed for different operating conditions, and this review also presents the advantages and disadvantages of the different circuit architecture combinations for multiband RF energy harvesting front-end systems. In summary, this review aims to fill the research gap in the further advancement of multiband RF energy harvesting towards enhancing its performance through optimal circuit integration of the front-end system.

An N-Path Sub-GHz Ultra-Low Power Receiver Exploiting an N-Path Notch Filter Topology in 90 nm CMOS

This paper describes an N-path sub-GHz ultra-low power receiver exploiting an N-path notch filter topology in 90nm CMOS process. The receiver achieves the flexibility in the operating frequency due to an adjustable internal impedance matching network with an N-path notch filter. The receiver consists of two current-reused topologies, which greatly simplifies the structure and achieves ultra-low power consumption. Specifically, the receiver incorporates: 1) an amplifier with an N-path notch filter, which acts as the first stage of the receiver to provide an input impedance of 50 Ω without an inductor. This input matching network is frequency flexible and adjustable to suit different frequencies of the input signal. Meanwhile, the N-path notch filter can suppress out-of-band interference to cope with limited frequency bands. 2) N-path passive mixers are reused for simultaneous filtering and down-conversion. 3) Amplifiers are frequency-division multiplexed to amplify both RF and baseband signals simultaneously. Finally, the receiver is fabricated in 90 nm CMOS and operates at 0.6 V supply voltage with a power consumption of 780 μW. The receiver achieves a conversion gain of 41.2 ± 3.2 dB, a noise figure of 5.7 ± 0.3 dB and an OB-IIP3 of 14.6 ± 0.5 dBm. The chip area of the implemented receiver is 0.08 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .

A 2.4-GHz Fully-Integrated GaAs pHEMT Front-End Receiver for WLAN and Bluetooth Applications

This paper describes a 2.4-GHz fully-integrated front-end receiver including a single-pole triple-throw (SP3T) switch and a low-noise amplifier (LNA) with bypass function, which was fabricated in a 0.25 μm GaAs pHEMT process. An asymmetrical SP3T switch architecture is incorporated to enable the receiver to operate in four modes. The exploration of impedance and voltage gain behavior of the proposed LNA help to establish the matching network and alleviate the trade-off between noise figure (NF) and gain performance. In LNA high gain mode, the implemented front-end receiver shows 1.7 dB of NF and 6dBm of input third-order intercept point (IIP3) with 20 dB of power gain drawing 11 mA of current from 5 V power supply at 2.4 GHz. All input and output return loss had exceeded 10 dB with fully on-chip impedance matching network. In bypass mode, the measured insertion loss of typically 7.5 dB is achieved.

임피던스 매칭을 포함하는 소형 광대역 집중소자-분산 발룬의 설계

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°

Near-field coupling and wireless signal transmission using a magnetoelectric laminated composite antenna

Magnetoelectric (ME) antennas utilize the direct or converse ME effects at acoustic resonance to receive or transmit electromagnetic (EM) signals, making ultra-compact antennas feasible. This work presents a miniaturized ME antenna working at very low frequency (VLF) band. A piezoelectric wafer and magnetostrictive foils are bonded together to form the 12×2.1×0.08 cm3 ME antenna. The near-field coupling between the ME antenna and magnetic rod coil has been measured to verify the reciprocity. The proposed entire circuit simulation models agree well with the experimental results, explaining the maximum power gap and frequency offset phenomenon. In addition, both practical and simulation results confirm that near-field coupling depends on mutual inductance rather than EM radiation. Based on the emulation of circuits, L-section impedance matching networks are introduced to improve the original power transmission coefficient by 21 dB. The ME antenna is lightweight, wide-band, and easy to match compared with a conventional coil.

Statistical analysis of radiofrequency energy harvester with bandpass filter for ultra‐low power applications

AbstractNowadays, radiofrequency (RF) is a vital component of harvesting RF energy from the ambient environment to power ultra‐low‐power applications in wireless communication. This article presents an RF energy harvesting system for a frequency range of (0.58–3 GHz) to harvest RF energy from the ambient source. The system's design consists of four major modules: a coplanar waveguide antenna (CPW), a bandpass filter (BF), an L‐type impedance matching network, and a four‐stage Villard voltage multiplier (VM) circuit. First, A CPW antenna is designed suitably to harvest RF energy from GSM 900/1800, 3G, and Wi‐Fi frequency bands. Next, a BF is designed and simulated in Agilent advanced design system software for the same frequency range to attenuate the RF signals that are not in this specific frequency range. Then, an RF power conditioning circuit prototype comprising an L‐type impedance matching network and a four‐stage Villard VM circuit was integrated and fabricated on an FR4 substrate. The four‐stage rectifier circuit is designed to convert the RF signal into DC output voltage and maximize the output voltage. The performance of the RF energy harvesting system is validated through simulation and measured results. All the RF energy harvesting system elements have been connected, and the prototype is tested at various indoor and outdoor locations of Sri Sivasubramaniya College of Engineering, Chennai, India. It is observed that the prototype system can harvest energy from input power levels as low as −30 dBm. The simulated results of the RF energy harvesting system achieve an output voltage of 2.5 V with a maximum efficiency of 62.5%. The harvested output voltage at a distance of 100 m from the RF cell tower at the indoor location is 59.5 mV and at the outdoor location 271.6 mV. The harvested output voltage is used to energies the ultra‐low‐power applications. Finally, the performance of the RF energy harvesting system is analyzed by statistical techniques. The two types of analysis are Taguchi's method and analysis of variance. The RF energy harvester impact factors are VM and BF. A statistical test (P) is used to determine the significant factors on the RF output voltage.

High-Selectivity FA-FA-Based Frequency Selective Surfaces Using Magnetoelectronic Dipole Antennas

A new method for frequency selective surface (FSS) with high selectivity, namely, filtenna–filtenna (FA-FA)-based technique, is proposed, which consists of two filtering antennas and impedance matching network. Based on the reciprocity theorem, the radiation null of filtenna can provide a stopband of the proposed FSS. In this work, it is validated by using a periodic array of back-to-back magnetoelectronic (ME)-dipole antennas with split-ring resonators (SRRs), and a slotted GND plane is used to connect the two ME-dipole antennas for impedance matching. Bandpass response of the proposed FSS is realized by the intrinsic high-pass characteristic of ME-dipole antennas and the bandstop characteristic of SRRs. Four transmission zeros (TZs) and three transmission poles (TPs) are generated, exhibiting a high-order filtering response. TZs and TPs are analyzed by equivalent circuit model and current distributions. The 3 dB fractional bandwidth ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mathrm {FBW}}_{\mathrm {3\,dB}}$ </tex-math></inline-formula> ) of 38.5% in the passband and the 20 dB fractional bandwidths <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$({\mathrm {FBW}}_{\mathrm {20\,dB}})$ </tex-math></inline-formula> of 8.7% in the lower rejection band and 13.8% in upper rejection band are obtained in this design. Finally, a prototype is fabricated and measured to further validate the proposed FA-FA-based technique. Simulated and measured results show that the proposed FA-FA-based FSS is with the distinct advantages, including wide passband, low profile, tunable TZs, and dual-polarized application, which verifies the proposed method of FSSs.

Efficient and Compact Tri-Band Rectifier With Large Frequency Ratio for WPT

In this letter, an efficient and compact tri-band rectifier with large frequency ratio is proposed, which adopts a novel low-cost direct current (dc)-pass filter structure in the design. Three large frequency ratio rectifiers are combined together by using diode arrays with a frequency-selective topology without additional impedance matching networks. The dc-pass filter is composed of microstrip line structures cascaded low-cost lumped components, which can effectively suppress the high-order harmonics at high- and low-frequency points while reducing the circuit size and costs of large frequency ratio. For validation, the proposed rectifier working at 0.915, 2.45, and 5.8 GHz is fabricated with the dimensions of 29.5 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times21.3$ </tex-math></inline-formula> mm. The measured results show that the RF-dc power conversion efficiency (PCE) reaches 72.6%, 71.8%, and 73.5% at 0.915, 2.45, and 5.8 GHz, respectively, when the input power is 19 dBm. Compared with traditional multiband rectifiers, the proposed topology exhibits merits of compact size, high efficiency, and large frequency ratio.