This paper presents a fully passive 2nd-order noise-shaping successive approximation register (SAR) analog-to-digital converter (ADC) designed specifically for low-power and low-cost Internet of Things (IoT) applications. By optimizing the coefficients, a substantial 24dB in-band quantization noise suppression is achieved. To further reduce power consumption and the total unit capacitor count, a hybrid switching procedure and optimal logic are utilized. The measurement result shows that this design achieves an effective number of 10.31 bits over a 3.125MHz signal bandwidth. At a power supply of 1.8V, the power consumption is measured to be 728µW with a sampling rate of 50MS/s. Fabricated in 180-nm CMOS technology, the ADC core occupies an area of 0.117mm². The Schrier figure-of-merit (FoM) of 160.13dB is obtained.

An integrated sensor for temperature (Temp) and humidity (RH) measurement is designed. The temperature and humidity (T/H) sensing probe are combined with one first-order discrete-time Σ-Δ analog-to-digital converter (ADC). Also, a new ample architecture of ADC is proposed, ADC selects a reasonable reference voltage according to varied range of T/H signals. Therefore, the dynamic range utilization rate of ADC is improved. The proposed sensor is designed and fabricated in 0.153μm CMOS technology. The experimental results show that the T/H sensor achieves a -0.9∼0.6% RH measurement accuracy in the humidity range of 10∼90% RH, and ±0.4°C temperature measurement accuracy in the temperature range of -40∼120°C.

This paper proposes a multicell-to-multicell (MC2MC) equalizer based on the half-bridge bipolar-resonant LC converter (HBBRLCC), which collects energy from the consecutive more-charged cells (high-voltage group) through the positive and negative polarity selection switch matrix and the half-bridge switch matrix, and then releases the energy to the consecutive less-charged cells (low-voltage group). The paper includes configuration of the proposed equalizer, the mathematical model and simulation comparison with conventional equalizers, highlighting the superior high-speed balancing performance and excellent balancing efficiency of the proposed equalizer. An experimental prototype is built with four cells to verify the performance, and the balancing efficiencies in different balancing modes range from 81.45% to 87.62% with an average balancing power of 1.454W to 5.011W.

This paper proposes a high-efficiency wideband continuous-class power amplifier (PA) optimizing the fundamental and harmonic impedance areas to achieve wideband and efficient operation. Unlike conventional impedance area constraint methods, reflection coefficient circles are used to characterize the desired fundamental and harmonic impedance areas, thereby increasing the number of feasible solutions in the output matching network (OMN) optimization. Additionally, a multi-objective algorithm is employed to optimize the OMN, enabling the PA to achieve high efficiency over wide frequency band. To validate the feasibility of the proposed method, a continuous-class PA operating in the frequency range of 1.5-2.6GHz is designed and measured. The results demonstrate that the PA achieves a saturated output power of 40-41.5dBm with a corresponding gain around 10dB. Maximum efficiency ranging from 68% to 75% can be achieved within the operating frequency range.

This paper introduces a novel balanced bandpass filter (BPF) that utilizes the symmetrical F-shaped groove (SFG) substrate-integrated waveguide and spoof surface plasmon polariton (SIW-SSPP) structure. This design combines lowpass SSPP unit cells within a highpass balanced dual-layer SIW structure to realize bandpass filtering response. The SFG SIW-SSPP unit cell’s superior dispersion properties contribute to broad bandwidth and extensive stopband. Additionally, the balanced dual-layer SIW structure, achieved by removing a rectangular aperture from the common ground, allows for high in-band common-mode (CM) suppression and a broad CM suppression range. The proposed filter offers multiple variables to regulate the passband’s lower and upper cut-off frequencies independently. A fabricated prototype of the balanced filter is tested, demonstrating superior performance compared to previously reported balanced SIW and half-mode SIW BPFs. The filter achieves a broad 3-dB fractional bandwidth of 46.55% (6.33-10.17GHz), a wide 20-dB stopband rejection up to 2 f₀ (f₀: the passband’s center frequency), and simultaneous broad CM suppression range (24-dB up to 4.85 f₀).

A modified Wilkinson power divider (PD) with improved in-band performance and compact size is proposed in this paper. Compared with conventional Wilkinson PD, such structure features with an additional shorted stub on the output port, which can introduce an extra transmission pole for in-band performance enhancement. Besides, the proposed Wilkinson PD adopts meander line for compact size. Furthermore, the isolation resistor is achieved with thin film resistance technology to avoid welding tolerance. To verify the mechanisms mentioned above, a modified Wilkinson PD operating at 7GHz is designed and fabricated in size of 8.2mm × 8.8mm (0.2λ_g ×0.19λ_g), with significantly benefit of compact, wide-band, low loss and well in-band loss flatness characteristic. The measured fractional bandwidth (FBW) is 57.1% (i.e., 5-9GHz) with insert loss of 3.2-3.4dB. Meanwhile, the return loss is less than 15dB.

A method is proposed for a hybrid power supply modulator (PSM) which consists of a wideband linear amplifier (LA), switching converters (SC), and a hysteresis comparator (HC) for an envelope tracking transmitter. By a compensation method of using a dual feedback network, the stability of the LA circuit is realized. A System in Package (SiP) structure based on separated gallium nitride (GaN) devices and the designed LA is proposed to achieve high performance, high reliability, and miniaturization. Ranging from -40∼100°C of operating temperature, the 3dB bandwidth of the proposed PSM can reach over 120MHz which achieves the maximum efficiency of 82% at an average output power of over 4W with 2.5∼4.5V power supply. Using a long-term evolution (LTE) 10MHz quadrature phase shift keying (QPSK) with Peak to Average Power Ratio (PAPR) of 6.5dB at 225∼512MHz, the envelope tracking transmitter is measured that the power added efficiency (PAE) is 58.95∼66.96%, Error Vector Magnitude (EVM) is 1.7∼2.36%.

Contrary to the issues of low sampling efficiency and high risk of cross-infection with the traditional method of throat swab collection, this study researched on automatic throat swab collection system. In order to collect throat swabs, it was necessary to identify and locate human face and oral information, which is why machine vision was used for dynamic navigation and positioning. Firstly, a deep learning approach was employed to identify the external contour of the oral cavity, enabling the localization of the collection area. Subsequently, real-time depth imaging was utilized to calculate the spatial coordinate information of the target area. Additionally, force control feedback was implemented at the end of the collection to ensure the safety by controlling the contact force the throat swab exerting on the human pharynx. Finally, a robotic arm was used as an executive agency to transport the pharyngeal swab to the designated target area for collection. The experimental results demonstrated that the automatic throat swab collection system successfully executed the planned path and obtained valid throat swab samples.

We have investigated a magneto-optical (MO) isolator fabricated by µ-transfer printing (µ-TP) method which enables tiny bonding area with a low-temperature process. Although excessive absorption loss can be reduced, the large junction loss at the boundaries of MO material cladding is still a problem. We propose two ultra-low-loss Mach-Zehnder interferometer-type MO isolators. The tapered coupon type isolator reduces the junction loss of TM mode. The TE input type isolator reduces the junction loss by propagation of TE mode instead of TM mode. We designed these structures and numerically demonstrated ultra-low-loss isolators with insertion losses of <2dB.

For general metallic cavities, the overmoded frequency is of critical for electromagnetic applications. In order to estimate the overmoded field behavior without a mechanical stirrer rapidly, a simple scattering parameters measurement-based procedure is presented, on which the samples will be obtained by mean of hybrid stirring technique, e.g., frequency and source stirring strategies. Then, the correlation analysis and coefficient of variation are used to deal with the samples, aiming to estimate the overmoded frequency. A comparison has been made between the results estimated by hybrid and mechanical stirring-based method, which highlights that the hybrid stirring-based method can be regarded as an alternative solution for mechanical stirring.

In this paper, we propose a novel methodology for designing a rectifier with wide input power range (WIPR). In the proposed structure, a two-port resistance compression matching network (RCMN) is employed to extend the dynamic range of the input power. Generally, resistance compression network (RCN) is developed based on three-port network theory. This leads to the conventional RCN-based rectifier has two sub-rectifiers and arranged in a dual-branch topology. Compared with the conventional RCN-based rectifier, the proposed two-port RCMN-based rectifier not only has a single-branch topology but also can work without using an individual impedance matching network. Thus, a compact size and lower circuit complexity can be achieved. The closed-form design equations of the proposed two-port RCMN are designed. For validation, a 2.45GHz WIPR-rectifier prototype is fabricated and tested. The experimental results show that the power convert efficiency (PCE) is higher than 50% when the input power varies from -2.1 to 13.1dBm. The peak PCE is 74.5% with a 10.2dBm input power. And its physical size is only 43mm × 24mm.