An external capacitor-less low-dropout voltage regulator using a transconductance amplifier

This paper presents an external capacitor-less NMOS low-dropout (LDO) voltage regulator integrated with a standard CSMC 0.6 μm BiCMOS technology. Over a -55 ∘C to +125 ∘C temperature range, the fabricated LDO provides a stable and considerable amount of 3 A output current over wide ranges of output capacitance COUT (from zero to hundreds of μF ) and effective-series-resistance (ESR) (from tens of milliohms to several ohms). A low dropout voltage of 200 mV has been realised by accurate modelling. Operating with an input voltage ranging from 2.2 V to 5.5 V provides a scalable output voltage from 0.8 V to 3.6 V. When the load current jumps from 100 mA to 3 A within 3 μs, the output voltage overshoot remains as low as 50 mV without output capacitance, COUT. The system bandwidth is about 2 MHz, and hardly changes with load altering to ensure system stability. To improve the load transient response and driving capacity of the NMOS power transistor, a buffer with high input impedance and low output impedance is applied between the transconductance amplifier and the NMOS power transistor. The total area of fabricated LDO voltage regulator chip including pads is 2.1 mm×2.2 mm

Innovative Engineering Education in Circuits and Systems

Nowadays, the field of microelectronics has become the drive for the advancement of the times, which promotes new demands on the cultivation of the students in colleges and universities. In order to keep up with the trend of the global engineering educational reform, three important reforms in education have been in progress step by step, including classroom teaching, innovative training and virtual laboratories. At first, for enhancing and integrating the existing courses related to the circuit, so that the students can comprehend the existing knowledge much more effectively, an important and effective curriculum reform has been performed by combining “Circuit Analysis” and “Analog Circuit Foundation” into one course; Then, innovative training has been carried out to cultivate the team skills among the students; Finally, in consideration of the rapid development of the electrical and electronic experiment, the conventional laboratory equipment may not satisfy the demand of every student due to financial constraints, therefore, the construction of virtual simulation experiment center is an efficient way to break this bottleneck. As a result, the atmosphere of academic innovation of the pursuit of truth, advocacy of science, brave exploration, dare to practice have been formed in colleges and universities through the above innovative engineering education reform

Integrating Fermentation Engineering and Organopalladium Chemocatalysis for the Production of Squalene from Biomass-Derived Carbohydrates as the Starting Material

The transition from fossil resources to renewable biomass for the production of valuable chemicals and biobased fuels is a crucial step towards carbon neutrality. Squalene, a valuable chemical extensively used in the energy, healthcare, and pharmaceutical fields, has traditionally been isolated from the liver oils of deep-sea sharks and plant seed oils. In this study, a biochemical synergistic conversion strategy was designed and realized to convert glucose to squalene by combining fermentation technology in yeast with reductive coupling treatment of dienes. First, glucose derived from hydrolysis of cellulose was used as a renewable resource, using genetically engineered Saccharomyces cerevisiae as the initial biocatalyst to produce β-farnesene with a titer of 27.6 g/L in a 2.5 L bioreactor. Subsequently, intermediate β-farnesene was successfully converted to squalene through the organopalladium-catalyzed reductive coupling reaction involving the formation of Pd(0)L2 species. Under mild reaction conditions, impressive β-farnesene conversion (99%) and squalene selectivity (100%) were achieved over the Pd(acac)2 catalyst at a temperature of 75 °C in an ethanol solvent after 5 h. This advancement may provide insights into broadening squalene production channels and accessing the complex skeletons of natural terpenoids from biorenewable carbon sources, offering practical significance and economic benefits