In this paper, we propose a new wideband microstrip phase shifter based on an RF transformer. The structure consists of two main components: a mainline and a reference line. The mainline is a bandpass filter that incorporates the coupling characteristics of the RF transformer to achieve the required bandwidth. The reference line is a uniform transmission line, and its electrical length is adjusted to control the phase shift. Compared to traditional phase shifters, this design offers several advantages, including a wide bandwidth, compact size, simple structure, and a large phase shift range. To demonstrate the effectiveness of the design, a phase shifter with a 90°-225° phase shift range was both designed and simulated. Additionally, a 90° phase shifter was fabricated and measured. The measurement results show that the phase shifter achieves a phase shift of 90° ± 2.1°, with an S11 of less than -10 dB and a fractional bandwidth (FWB) of 63.25%.

This letter proposes a high-linearity bootstrapped switch designed for application in SAR ADC. The proposed switch introduces an auxiliary capacitor branch to the conventional bootstrapped switch. By connecting other branches on the bootstrap signal channel to the auxiliary capacitor branch, the capacitor parasitic effect on the bootstrap signal channel is diminished, thereby reducing the overall parasitic capacitance of the circuit and improving both the linearity of the sampling switch and its response speed to signals. Simulation verification based on a 55 nm CMOS process library demonstrates that at a sampling frequency of 10 MHz, the proposed structure achieves an signal-to-noise-and-distortion ratio (SNDR) of 89.86 dB, and an spurious-free dynamic range (SFDR) of 94.52 dBc.

A vector-processor architecture based on the RISC-V extended instruction set is proposed and evaluated for the acceleration of post-quantum cryptographic (PQC) algorithms. The core employs an in-order, partially four-way multi-issue pipeline and delivers a significant speed-up over pure-software RISC-V implementations. Unlike previous hardware-software co-designs that target specific PQC schemes, the instruction-set extensions are derived from fine-grained, fixed-point arithmetic primitives; consequently, the same core can speed up current NIST candidates and tolerate future algorithm updates while remaining useful for other cryptographic workloads. The processor was implemented in 28 nm SMIC HKE+ process, and post-layout simulations were conducted. Results showed that under primary PQC standards, compared with the state-of-the-art counterparts, it can achieve a reduction in total cycles by 9.1%-12.7%. In terms of stream cipher, block cipher, and hash cipher algorithms, it can achieve 12×-24× performance improvement, which enables it to have higher flexibility in practical application scenarios.

The wireless power transfer (WPT) system is widely used for its convenience. However, how to address the problem of misalignment is a hard problem to solve. This paper proposes a design method for an output-parallel Series-Series (SS) WPT system based on a designed splitting coil coupler. The method aims to optimize the parameters of coil structure based on the multi-island genetic algorithm. Besides, by designing splitting coils and specific parameters, the performance of misalignment tolerance of multi-channel coils is improved, and the detailed analysis is proposed as well. Finally, A 3.3 kW splitting coil WPT system prototype is built. Compared to the traditional design, the proposed design can achieve a higher coupling with the same misalignment distance, as well as less power loss by the designed splitting coils.

In non-laboratory settings, high-precision detection of methane gas is vulnerable to noise and environmental interference. To address this issue, we propose a methane detection system that utilizes tunable semiconductor laser absorption spectroscopy technology combined with second harmonic detection. This system employs a hardware-algorithm collaborative design architecture to effectively suppress noise. In comparison to commercial non-dispersive infrared sensors, the detection limit of our system is reduced to 4.81 ppm, demonstrating enhanced long-term stability. The Allan variance is measured at 4.38 × 10^-7 over a duration of 147 seconds. Experimental results indicate that the system exhibits good response linearity within the range of 0-1000 ppm, with a coefficient of determination (R²) of 0.9818. This research offers a reliable solution for industrial methane monitoring, and the portable design concept may serve as a valuable reference for the development of other gas sensing systems.

For wireless power transfer systems, constant current (CC) output, constant voltage (CV) output, and zero phase angle (ZPA) switching are critical research priorities. This paper proposes an LCC-LCC/S hybrid compensated converter integrated with an auxiliary switch-controlled capacitor (SCC). By adjusting the parameters of the SCC, the LCC-LCC compensation topology can achieve load-independent CC output at a fixed frequency under ZPA conditions. Similarly, the LCC-S compensation topology enables load-independent CV output under the same operating conditions. Experimental validation is conducted on a 19.42 kHz prototype, which stably delivers 2 A and 60 V with a peak efficiency of 90.7%.

A compact fundamental 140 GHz mixer using our in-house 80 nm T-gate InP HEMT process is designed, fabricated and characterized. A compact resistive topology is designed to enable low power consumption, high conversion gain and high integration. Measurement results show a maximum conversion gain of -9 dB and an IF bandwidth of 15 GHz within the 130 GHz-150 GHz range under a LO power of -1 dBm. The proposed resistive mixer features a compact size of 0.63 mm × 0.9 mm and can be fabricated with InP HEMT LNA on the same wafer. The results demonstrate that the mixer is well suited for integrated terahertz receiver front-ends.

Accurate modeling of self-heating effect in power transistors is crucial for reliable design and performance evaluation of wireless communication circuits and systems. This letter presents an enhanced time delay neural network (TDNN) technique specifically developed to model power transistors considering self-heating effect. At first, an enhanced TDNN model topology suitable for power transistors is proposed. To accurately describe the self-heating effect, a thermal sub-circuit is incorporated into the model framework. Moreover, novel formulations for direct current, small-signal S-parameters, and large-signal harmonic balance outputs of the proposed TDNN are derived so that typical measurement data can be utilized for model training. Finally, training algorithm is also proposed to effectively optimize the weighting and thermal parameters in the proposed TDNN model. The effectiveness of the proposed technique is validated through a modeling example involving a practical power transistor. The resulting TDNN model is embedded in Keysight Advanced Design System, and simulation results based on this model demonstrate good agreement with the measured data.

This paper proposes a disturbance-observer-based tuning-free controller (TFC) for magnetic-geared motors (MGM). To address the difficulty of conventional active damping controllers (ADC) in suppressing the flexible elements of magnetic gears and load inertia disturbances in MGM applications, a disturbance observer is introduced to enhance robustness. A detailed parameter design procedure is provided in the discrete domain, and theoretical analysis compares the suppression performance of the conventional ADC and the proposed TFC. Finally, experiments on the MGM prototype platform demonstrate that the proposed TFC exhibits stronger robustness against load inertia disturbances.

This letter presents a novel five-order Ka-band bandpass filter based on micro electromechanical system (MEMS) technology. The basic structure using air-filled with internal coupled lines and fully enclosed metal cavity has advantages of low dielectric and radiation loss, compact size, which is conductive to the design of high-frequency passive components. The resonant unit consists of metal cavity and parallel arranged open and short-circuited metal cores. Detailed design method is given to guide the Ka-band filter design. Moreover, it demonstrates the successful application of classical microstrip filter synthesis theory to the design of a complex 3D cavity-based MEMS filter. To enable easy integration with RF systems, a standard 50-Ω interface with ground-signal-ground (GSG) transition is added to the designed filter. Finally, the filter is fabricated and measured, and good agreements between the simulated and measured results are achieved.

This letter introduces a design methodology for a broadband high-efficiency power amplifier (PA) that incorporates a new symmetrical triangular low-pass filter with Embedded Radial Stub. To extend the design space, a resistive-reactive series of continuous inverse modes (Res.-Rea. SCIMs) theory is employed. The proposed filter, which serves as the output matching network of the PA, is constructed with dual-triangular symmetric (DTS) microstrip lines and a radial stub, which are interconnected by microstrip lines. By combining a DTS filter and a radial stub, a new filter with improved performance has been proposed. The new filter achieves low passband loss, high out-of-band rejection, and narrow transition bandwidth. These characteristics are well utilized in the inverse Class-F power amplifier, resulting in excellent performance. It is applied to the output matching circuit to realize a broadband high-efficiency PA. To validate the effectiveness of the proposed structure, a PA prototype is designed and fabricated with a 10-W GaN HEMT device. Measurement results demonstrate a bandwidth from 0.6 GHz to 1.4 GHz, with a drain efficiency (DE) of 66.3%-73.3%, a gain of 9.53-12.17 dB, and an output power of 39.53-42.17 dBm.

The interconnection harness undertakes the critical task of power and signal transmission between in-vehicle electronic devices, and its electromagnetic compatibility (EMC) constrains the safety of vehicle systems. As the number of in-vehicle electronic devices increases and wiring becomes increasingly complex, the electromagnetic interference (EMI) issue between cables has become more prominent. Multiconductor transmission line (MTL) models suffer from limited computational efficiency when applied to the electromagnetic analysis of complex automotive wire harnesses. Although the equivalent cable bundle method (ECBM) offers an effective means of model reduction, it is commonly developed under the assumption of an ideal infinite conducting ground plane, which restricts its applicability in realistic vehicular environments characterized by finite metallic boundaries. To overcome this limitation, this paper presents an enhanced electromagnetic modeling approach within the ECBM framework, in which the effects of orthogonal finite metallic boundaries are explicitly incorporated into the per-unit-length parameter extraction. The proposed method is therefore well suited for automotive electromagnetic environments dominated by a limited number of nearby metallic structures. Simulation results demonstrate that compared with the MTL model, the proposed method can accurately predict crosstalk responses and radiation characteristics, with the simulation efficiency improved by approximately 50%. This method provides a new solution for vehicle EMC design and analysis.

Photoacoustic imaging is a hybrid imaging modality that combines optical and ultrasound imaging, achieving the high contrast of optical imaging together with the high resolution of ultrasound imaging. Although commercial preclinical devices for photoacoustic imaging are available, they often suffer from a limited angle of view. In this paper, we present a three-dimensional (3D) photoacoustic imaging system employing a hemispherical ultrasound probe to overcome this limitation. Using the proposed system, we demonstrate the visualization of carotid thrombosis in a mouse model.