In this study, a local positive feedback technique is proposed to enhance the performance of the folded cascode (FC) operational transconductance amplifier (OTA) when working in its saturation region. The enhanced FC-OTA has a higher gain bandwidth (GBW), higher DC gain and higher slew rate (SR) over its conventional counterparts and popular recycling FC-OTAs. The proposed enhanced FC-OTA is implemented by reusing the current generated by the input transistors through the proposed local positive feedback loop to provide additional transconductance and negative resistance. It is then fabricated with SMIC 180nm process. To verify the effectiveness of the proposed FC-OTA performance enhancement strategy, extensive mathematical analysis, small-/large-signal stability analysis, simulation and experimentation are thoroughly investigated in this study. Simulation and experimental results agree well with the theoretical analysis and the expected performances, which corroborates the control design.

An adaptively biased low dropout regulator (ABLDO) with current mirror buffer has been proposed in previous literatures, which only solves a few of specific problems of AB-LDO without additional synthetical analysis of the various performances. Based on the analysis, it is found that enhancing the current efficiency of operational transconductance amplifier (OTA) is a key factor to improve the performances of ABLDO. And a current reusing current-mode OTA (CRCM-OTA) with high current efficiency is proposed to apply to AB-LDO. Compared with the traditional AB-LDO, it can achieve an obvious improvement of AB-LDO performances including the current efficiency of AB-LDO, loop gain and loop bandwidth without increasing the area and power consumption. This paper also adopts an intuitive method different from the previous works to analyze the whole loop. The AB-LDO using an advanced CRCM-OTA was fabricated in SMIC 0.18μm CMOS process, which has a transient undershoot of 26.25mV with an output capacitor of 1μF for a load step of 0-50mA with edge time of 10ns and realizes a performance figure of merit (F oM) value of 13.65ps.

In this study, a 0.8-V- $V_{in}$ 200-mA- $I_{o}$ capless low-dropout voltage regulator (LDO) is developed for a wireless respiration monitoring system. The biaxially driven power transistor (BDP) technique is proposed in the LDO, with a current driven stimulation on the bulk and a voltage on the gate terminal. With the BDP technique, an adaptively biased current-driven loop (ABCL) is designed which can reduce the high threshold voltage of power transistor, thus presenting lower input voltage and reduced power consumption. Moreover, this loop can provide an improved dynamic response due to its increased discharging current. Based on an error amplifier with enhanced DC gain and gain bandwidth, the capless LDO achieves superior power supply rejection (PSR) and stability without a complex frequency compensation mechanism. The proposed LDO is fabricated in the SMIC 180 nm process with a chip area of 0.046 mm $^{2}$ . Measurement results indicate that this LDO can obtain a 200-mA load current range and greater than -66 dB PSR up to 1 kHz at a supply voltage as low as 0.8 V.

In both plastic surgery and burn treatment departments, the management of postoperative wounds is a crucial element of surgical care, profoundly influencing patient recovery and the broader spectrum of healthcare outcomes. The monitoring of wound flatness after surgery, although a pivotal component of this process, is frequently underemphasized. In most cases, this parameter can only be judged based on doctors’ personal experience. Here, we propose a compact, fully integrated wireless sensing system encapsulated by soft biocompatible materials for quantitative assessment of wound flatness and long-term temperature. The absence of physical tethers and the ion-gel-based construction of the micro-structured sensor represent key defining features, resulting in high measurement resolution of 2 mm radius and 0.096 Ω/°C and reliable capabilities. In addition, these sensors can be connected to the server network or mobile clients to evaluate the state of postoperative suture wounds and monitor the patient’s recovery status. With our devices, detailed data on smoothness and temperature of sutured wounds can be collected, analyzed, and stored for medical assistance as well as being used to improve the quality of surgery.