Current Issue : January-March Volume : 2026 Issue Number : 1 Articles : 5 Articles
This work presents a low-power photoplethysmography (PPG) readout integrated circuit (IC) that achieves a wide dynamic range (DR) through the direct integration of a voltagecontrolled oscillator (VCO)-based quantizer into the photodiode driver. Conventional PPG readout circuits rely on either transimpedance amplifier (TIA) or light-to-digital converter (LDC) topologies, both of which require auxiliary DC suppression loops. These additional loops not only raise power consumption but also limit the achievable DR. The proposed design eliminates the need for such circuits by embedding a linear regulator with a mirroring scale calibrator and a time-domain quantizer. The quantizer provides first-order noise shaping, enabling accurate extraction of the AC PPG signal while the regulator directly handles the large DC current component. Post-layout simulations show that the proposed readout achieves a signal-to-noise-and-distortion ratio (SNDR) of 40.0 dB at 10 μA DC current while consuming only 0.80 μW from a 2.5 V supply. The circuit demonstrates excellent stability across process–voltage–temperature (PVT) corners and maintains high accuracy over a wide DC current range. These features, combined with a compact silicon area of 0.725 mm2 using TSMC 250 nm bipolar–CMOS–DMOS (BCD) process, make the proposed IC an attractive candidate for next-generation wearable and biomedical sensing platforms....
In this paper, a compact wideband filtering monopole is presented for remote terrestrial omnidirectional communication systems. The presented antenna features a sleeve monopole structure integrating with two key components: the lumped parallel RLC circuits and an embedded high–low impedance structure within the sleeve section. The integrated high– low impedance structure enables the monopole to achieve excellent filtering characteristics while maintaining the monopole compactly. Meanwhile, the combination of the RLC loads and the sleeve monopole ensures wideband omnidirectional radiation performance. To validate the design, a prototype operating from 200 to 1500 MHz is fabricated and tested. The measurement results demonstrate that the monopole achieves a VSWR below 3 across the entire operating band and a measured gain exceeding 0 dB. Furthermore, the monopole exhibits satisfactory out-of-band rejection from 1700 to 4000 MHz, confirming its effective filtering capability....
This study used stair-embedded force plates to investigate the effects of lower-limb muscle fatigue on dynamic postural control during stair descent in young adults. Twenty-five healthy male adults (age = 19.2 ± 1.5 years) were tested for stair descent gait in pre-fatigue and post-fatigue conditions. To induce fatigue, participants performed a sit-to-stand task. The kinematic and kinetic data were collected synchronously, and gait parameters were analyzed. Data were analyzed using one-dimensional statistical parametric mapping (SPM1d) and paired t-tests in SPSS. After fatigue, the right knee flexion angle increased significantly across all phases (0–14%, p < 0.001; 14–19%, p = 0.032; 42–50%, p = 0.023; 60–65%, p = 0.022; 80–100%, p = 0.012). Additionally, the step width widened notably (p < 0.001), while the proportion of the swing phase decreased (p = 0.030). During the event of right-foot release, the left knee flexion (p = 0.005) and ankle dorsiflexion (p = 0.001) angle increased significantly, along with a larger left ankle plantarflexion moment (p = 0.032). After fatigue, the margin of stability in the anterior–posterior direction (MoS-AP) (p = 0.002, p = 0.014) and required coefficient of friction (RCOF) (p = 0.031, p = 0.021) significantly increased at the left-foot release and right-foot release moments. This study demonstrates that lower-limb muscle fatigue increases dynamic instability during stair descent. Participants adopted compensatory strategies, including widening step width, reducing single-support duration, and enhancing ankle plantarflexion to offset knee strength deficits. These adaptations likely reflect central nervous system mechanisms prioritizing stability, highlighting the ankle’s compensatory role as a potential target for joint-specific interventions in fall prevention and rehabilitation. Future studies should investigate diverse populations, varying fatigue levels, and comprehensive neuromuscular indicators....
This study presents the design and experimental evaluation of a 10 MHz voltage regulator module (VRM) that incorporates a solenoid inductor embedded within a printed circuit board (PCB). To verify the performance of the inductor, a test PCB was fabricated and characterized using a vector network analyzer (VNA), with measurement data processed through 2x-thru de-embedding technique. A 10 MHz VRM was then implemented to assess the impact of the embedded inductor on system efficiency. Comparative measurements were conducted between two VRMs—one employing a surface-mounted (SMT) inductor and the other a PCB-embedded inductor. The SMT-based system achieved a peak efficiency of 65.24% at a load current of 800 mA, whereas the PCB-embedded inductor version reached 70.43% at 900 mA, reflecting an improvement of 5.19%. The VRM with an embedded inductor experienced less efficiency degradation under heavy load conditions, demonstrating superior energy delivery stability. These findings confirm the practical benefits of integrating solenoid inductors within a PCB for high-frequency, high-efficiency power conversion....
The growing demand for electronics engineers is one of the cornerstones of STEM education. Recent trends in education show an extension of the STEM principle into STEAM by mixing Arts with the traditional Science, Technology, Engineering, and Math disciplines. Especially in elementary education, this has beneficial effects by increasing the appeal of STEM disciplines. This STEAM principle is less studied in university settings, but it can be beneficial for engineering students as well. This paper presents a case study of extending an Embedded Systems Programming class to include GUI design elements. Employing graphical user interfaces in embedded devices has been an increasing trend in the last decade, and there is also demand for introducing it into courses concerning embedded systems and microcontrollers. Teaching engineering students about graphic design has two main benefits: it increases the appeal of the course and also leads to better understanding the interaction between the two worlds of Arts and Engineering. The survey results of students after finishing the course show a high satisfaction level....
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