This work presents a sub-nanowatt voltage reference (VR) achieving a high-power supply ripple rejection (PSRR). It utilizes a self-current biasing circuit to reduce the voltage dependency of the output voltage (VREF) to the power supply variations. For low-power operation, all transistors operate in the subthreshold region. The design's performance is verified through post-layout and Monte Carlo simulations in a standard 180 nm CMOS process. Results show that the proposed bandgap achieves an output voltage of 0.150 V with a PSRR of -81.5 dB at V­­dd = 1V. Notably, it eliminates the need for an additional startup circuit and consumes only 0.72 nW at T = 27°C with Vdd = 0.5V. The proposed voltage reference exhibits a temperature coefficient (TC) of approximately 18 ppm/°C over a temperature range of -20°C to 130°C while without using a trimming circuit a reasonable (σ VREF /μVREF) = 2.3% is obtained. This design's average line sensitivity (LS) is 0.072%/V (Vdd = 0.5V to 1.8V). However, the PSRR and LS values are temperature-dependent. At the high temperature of 130°C (worst-case), the PSRR and LS degrade to approximately -80.45 dB and 0.084 %/V, respectively.  The output noise at the frequency of 1 KHz is obtained as 167.34 nV/ √ Hz. The proposed VR occupies a small active area of 513.5 μm2.

Resin-based composite restorative materials have a substantial share in dental treatments. Their esthetic has made them patients’ first choice as restorative materials. Marginal leakage is one of their problems which leads to recurrent caries and post-operative hypersensitivity. Our aim was to evaluate the theoretical and clinical methods that have been proposed in the dental literature. Around 50 articles from Pubmed, SCOPUS and google scholar were selected and categorized in 4 groups based on the selected keywords. All the studies discussed in this paper have emphasized that there is no way to eliminate the microleakage but it can be reduced by means of some approaches. On the other hand, due to the multifactorial nature and difference of oral environment and laboratory conditions, there isn’ t any certain way to define precisely. It seems that there is an absolute need for more research in this field to make the relation of theoretical results and clinical findings possible.

The devices with additional gates like Fin Field effect transistor (FinFET) provide higher control on subthreshold parameters and are favorable for Ultra large-scale integration. Also, these structures provide high control on current through the channel and with minimum leakage. In this paper we designed a FinFET with high-K gate dielectric material i. e Hafnium oxide as gate oxide. A comparison of similar sized transistor with Air and Silicon dioxide as gate material is performed. The comparison is mainly in terms of performance parameters like transconductance, subthreshold slope, and drain current characteristics. There is an increase in ON current on using a high-K dielectric material and subsequently an improvement in other parameters like subthreshold slope, transconductance and intrinsic gain.

Low power consumption, low chip area and fabrication in the standard complementary metal oxide semiconductor (CMOS) process are vital requirements for oscillators used in low-cost bio-implantable and wearable devices. Conventional ring oscillators (ROs) are good candidates for using in biomedical applications. However, their oscillation frequency strongly depends on the temperature. In this study, a temperature compensated ring oscillator with low power consumption is proposed. The transistors of the proposed ring oscillator operate in the subthreshold region to achieve a low power and low voltage performance. Since, in the subthreshold region, the oscillation frequency of a conventional ring oscillator increases with increase in the temperature, two current sources are used to power the proposed subthreshold ring oscillator: a temperature independent current source and a complementary to absolute temperature (CTAT) current source. In the proposed circuit, the CTAT current forms a small part of the total supplied current and its duty is to compensate for the oscillation frequency deviation. Two prototypes of the subthreshold ring oscillator were designed and simulated for a target frequency of 1MHz using commercially available 0.18µm RF-CMOS technology. The thermal coefficient (TC) of the uncompensated ring oscillator was 2400 ppm/ºC from -40ºC to 85ºC, though applying the proposed technique reduces the TC of the ring oscillator to 80.4 ppm/ºC with total power consumption as low as 14.5µW.

Purpose: To investigate the therapeutic effect of clinically invisible subthreshold continuous wave autofluorescence‑ controlled laser treatment on visual acuity and macular status of patients with chronic central serous chorioretinopathy (CSCR). Methods: In this prospective case series, patients with clinical and fluorescein angiographic (FA) findings of CSCR and chronic visual loss (>6 months) were included. Complete ocular examination, FA, and optical coherence tomography (OCT) tests were performed. Each eye was subjected to a direct laser treatment of leakage points by 532 nm continuous wave low energy laser pulses, which were kept invisible by reducing the power to 70% of the threshold test spot. Considering the lack of visible effect on the retinal pigment epithelium (RPE), the laser effect was monitored by pre‑ and post ‑ treatment infrared and autofluorescence images. Results: A total of 20 patients were included in this study, of whom 12 patients (9 male and 3 female patients) with an average age of 38 years had complete follow‑ up (Average: 3. 5 months). The mean preoperative visual acuity was 20/80, which improved to 20/40 at the final visit. The mean preoperative central macular thickness (CMT) was 330 µ m and the average final CMT in the last OCT test was 188 µ m (P = 0. 001). Conclusion: Subthreshold continuous wave autofluorescence‑ controlled laser treatment may be a good treatment for chronic CSCR to avoid the risks of retinal damage by clinically suprathreshold laser therapy.