Microwave and Optical Technology Letters最新文献

This paper presents a Ka-band flat-gain low-noise amplifier (LNA) in 65-nm CMOS technology. An optimized gate bias technique is utilized for comprehensive optimization among noise figure (NF), input 1 dB compression point (IP_1dB), and power consumption. Then a current-reused technique is used to further reduce power consumption, and an inductor is inserted in the current-reused DC path to improve the circuit's common mode stability. The interstage and output magnetic-coupled resonator (MCR) matching network with individual pole manipulation is optimized to achieve an enhanced gain flatness. From the measurement results, S21 of 14.8–15.5 dB is achieved from 26.5 to 29.5 GHz, with a gain ripple of 0.7 dB. Measured NF varies from 2.85 to 3.3 dB, with the lowest NF at 27.5 GHz. The measured IP_1dB at 28 GHz has achieved as high as −12.5 dBm. The whole LNA consumes 6.8 mW under a 1-V supply, achieving a high FoM of 25.31 Hz in dB (dBHz). The fabricated LNA occupies a core area of 0.1 mm².

A circularly polarized (CP) filtering patch antenna based on parasitic patches with slots is presented. The structure consists of one CP feeding network, one driven patch, and two parasitic patches. Two radiation nulls (RNs) are caused when the parasitic patches with slots are introduced, and the locations of RNs could be controlled by the slot length. Besides, the impedance bandwidth and axial ratio (AR) bandwidth are both improved compared to the antenna without parasitic patches. A prototype is fabricated and measured. The impedance bandwidth is 14.9% (3.42–3.97 GHz), and the 3-dB AR bandwidth is 8.9% (3.53–3.86 GHz). The realized gain at center frequency of 3.70 GHz is high up to 8.1 dBiC. Two radiation nulls at 2.95 and 4.55 GHz are generated. The proposed CP filtering antenna has the advantages of simple structure and easy fabrication, and can be a promising choice for wireless communications.

This paper presents a filtered power amplifier (PA) based on the continuous class-F mode. This broadband filtering PA employs a terminated coupled line structure, which consists of coupled line segments and four terminations loaded on them for obtaining high efficiency over a wide frequency band. Also, a detailed theoretical analysis and calculation of the proposed termination coupling line structure is given. The filter plays the role of filtering and impedance matching simultaneously, and thus high-order harmonics of the filtering PA are suppressed. For verification, the proposed PA is designed, fabricated, and measured. The measurement results show that a drain efficiency of 60.5%–69.8%, a gain of more than 10 dB, and an output power of 40.2–42.4 dBm are achieved in the target frequency band.

A 24.8–29.1-GHz four-stage gallium nitride (GaN) low noise amplifier (LNA) monolithic microwave integrated circuit (MMIC) is presented in this letter which is fabricated in a 0.15-μm GaN-on-SiC process. The proposed GaN LNA utilizes gate/drain bypass networks and source degeneration (SD) to achieve both 0–40-GHz unconditional stability and broadband simultaneous noise and input matching (SNIM). The measured results show a peak gain of 19.9 dB with a 3-dB bandwidth of 4.3 GHz and a low noise figure (NF) of 1.58–2.57 dB. The input and output return losses are better than 11 dB and the output-referred third-order intercept point (OIP3) is greater than 21 dBm. The presented LNA has a core area of 4.2 mm² and consumes a power dissipation of 150 mW. Compared with other state-of-the-art GaN LNA designs, the proposed LNA exhibits competitive NF and overall performance.

This study presents a substrate integrated waveguide (SIW) broadband circularly polarized (CP) high-gain low-profile magneto-electric dipole antenna array. The antenna array is characterized by wide impedance bandwidth (IBW), novel CP operating principle, small form factor, and good radiation performance. First, the antenna element consists of a two-layer dielectric substrate, two pairs of magneto-electric dipoles, and a SIW cavity coupled and fed through a cross-shaped rectangular slit. To achieve a wide CP bandwidth (BW), a pair of magneto-electric dipoles is rectangularly chamfered and then an “L” type parasitic patch is introduced. The simulation results show that the antenna element has an axial ratio (AR) BW of 14.2% in the 31.48–36.16 GHz range, the IBW in the 29.08–35.98 GHz range is 21.2%, and the gain is greater than 8 dBic in all bands. The antenna exhibits stable patterns and wide overlap IBW (31.48–35.98 GHz). Then, a planar 2 × 2 antenna array fed by a one-part-four SIW power divider was designed, fabricated, and measured. The measured results show that the array has an ARBW of 14% in the range of 31.29−35.83 GHz, an IBW of 21.8% in the range of 29.28–35.83 GHz, and a peak gain of 14.1 dBic.

In this letter, a method of designing quasi-elliptic bandpass filter with ultrabroad reflectionless bandwidth and high selectivity is proposed. It is implemented on the basis of a quasi-elliptic absorptive lowpass filter (ALPF) prototype that features both a low-reflection response over all normalized frequencies and two controllable transmission zeros near the passband. A distributed-element absorptive bandpass filter (ABPF) scheme using coupled-line units is derived from this quasi-elliptic ALPF prototype. With this distributed-element ABPF scheme, both ultrabroad reflectionless bandwidth and compact size can be realized. Equations for closed-form design are derived. A microstrip ABPF operating at 2.0 GHz (i.e., f₀) is designed for validation. The measured roll-off rates of the upper and lower transition bands are 116.44 and 157.41 dBc/GHz, respectively. The return loss is better than 10 dB from direct current to 6.25f₀. The size of the overall circuit is 0.12λ_g².

In this paper, a design procedure of a compact broadband microstrip diplexer working on the Very High Frequency (VHF)/Ultrahigh Frequency (UHF) band is proposed. The diplexer consists of a fourth-order Butterworth Low-Pass Filter (LPF) and a sixth-order elliptic High-Pass Filter (HPF). The two filters are located on two substrates with a common ground. A microstrip-to-coaxial structure is utilized to transmit the power flow between the two substrates. For miniaturization, the utilized ideal capacitors and inductors are realized by the commercial lumped-element capacitors and the curved microstrip line sections, respectively. All the middle design and rapid optimization processes from the schematic simulation by Advanced Design System (ADS) to the circuit simulation by CST STUDIO SUITE (CST) are given in the article. A prototype is fabricated and measured. The testing results are consistent with the simulation. The diplexer can operate at 225–775 and 880–2500 MHz. The insertion losses are 0.8 ± 0.3 and 0.9 ± 0.4 dB in the two working bandwidths. The isolation bandwidth of −20 dB level is as small as 105 MHz. The roll-off is also sharp that the related bandwidths corresponding to the attenuation level −3 to −20d B are 90 and 30 MHz to the high and low bands, respectively. Besides, the return loss and isolation are larger than 10 and 20 dB approximately. The diplexer has a volume of 0.065 λ_g × 0.156 λ_g @775 MHz, which can be utilized to feed the miniaturized broadband VHF/UHF antenna system.

In this paper, a quasi-lumped element-based bandpass filter is implemented by substrate-integrated suspended line (SISL) technology. To miniaturize the filter size, a deep hole drilling capacitor (DHDC) structure is proposed. The properties of DHDC are derived by parametric analysis and equivalent circuit analysis. Based on derived properties, a quasi-lumped element bandpass filter using SISL technology is designed and fabricated. Experimental results demonstrate that the proposed bandpass filter achieves the center frequency $��\; ��f_0��$ of 1.48 GHz, with a fractional bandwidth of 50%. The minimum insertion loss within the passband is 0.96 dB, while the return loss exceeds 23.14 dB. The maximum out-of-band suppression is over −50 dB, and the filter size is only 0.172 λ_g× 0.062 λ_g.

A chalcogenide (ChG) multi-slot waveguide gas sensor with ChG as the core layer and silicon dioxide (SiO₂) as the under-cladding layer is proposed. Multi-slot waveguide can be used in the mid-infrared gas measurement. The optimized power confinement factor (PCF) of the ChG multi-slot waveguide can be up to 41.3%, which is ∼20% higher than that of the optimized single-slot waveguide. At the absorption line located at 3.291 μm for methane (CH₄) measurement, the limits of detection (LoD) of single-slot, double-slot, triple-slot, quadruple-slot waveguide sensors are determined to be 68.9, 57.4, 52, 48.6 parts per million (ppm), respectively. Compared with other waveguide sensors in the mid-infrared, the PCF of the proposed multi-slot ChG/SiO₂ waveguide sensor is enhanced by five times, which has the potential for highly sensitive gas sensing.

This letter details the design and implementation of a millimeter-wave (mm-Wave) low noise amplifier (LNA) employing 150-nm gallium nitride on silicon carbide (GaN-on-SiC) high electron mobility transistor technology, specifically tailored for fifth-generation (5G) applications. The proposed GaN-based LNA integrates a hybrid matching topology alongside a co-design strategy, thereby optimizing the noise figure (NF) by minimizing interstage matching components. The fabricated LNA, spanning a total chip area of 2.3 × 1.4 mm², exhibits a linear gain in the range of 17.41–19.2 dB and maintains an NF within 2.32–3.06 dB. Additionally, commendable input/output return losses exceeding 7.5 dB are achieved across the 23–27.5 GHz, with the apparatus consuming approximately 150 mW.