Aiming at the error problem in estimating the speed of a permanent magnet synchronous motor (PMSM) using a sliding mode observer in a flywheel energy storage system, a super twist sliding mode observer (SMO) is used to replace the traditional sliding mode observer. A new saturation function is designed to replace the sign function. In addition, a constant sliding mode gain may lead to a decrease in observation accuracy during speed switching. An adaptive sliding mode gain is proposed to reduce chattering, The accurate estimation of the comprehensive speed range observer is enhanced, and the stability of the proposed observer is proved. On this basis, a super twist sliding mode speed controller is designed to replace the traditional PI controller to improve the observation performance of the system. The flywheel energy storage system’s simulation model is built, and the flywheel energy storage system’s constant speed standby and charging conditions are simulated. The simulation results verify the correctness and effectiveness of the improved super twist sliding mode observer in the flywheel motor.

Due to the advantages of low harmonic, low pollution to the power grid, and easy filtering, multilevel inverters have attracted more attention in recent years. In this paper, a five-level inverter based on the differential structure is proposed. It doesn’t need an additional bridge arm to change the polarity of the output voltage, but synthesize the structure of generating multiple voltages and changing the polarity of the output voltage. In addition, the special symmetrical structure of the inverter solves the problem of unbalanced capacitor voltage. The proposed five-level inverter is simulated by MATLAB/Simulink and the prototype is made to experiment.

A high voltage, external capacitor-less low-dropout regulator (HVLDO) with transient enhancement loop is presented in this work. The proposed HVLDO is designed with high withstand voltage laterally-diffused MOS (LDMOS) transistors and a transient enhancement loop is proposed to properly inject/sink current to/from the gate and output nodes of the power transistors to achieve fast transient response and high stability. Fabricated in 0.5µm SOI BCD process, the HVLDO occupies an active area of 0.29mm². Operating with an input voltage ranging from 5.2 to 20V, it supplies an output voltage of 5V and a maximum load of 100mA. For all load conditions, this design has the power supply rejection of -49dB@100kHz, the phase margin over 68.4deg and achieves a temperature coefficient of 13.15ppm/°C. Measurement results show that this design has a line regulation of 0.88mV/V and a load regulation of 0.22mV/mA. The proposed HVLDO features fast line transient response of 60/20mV@9.8V/µs, fast load transient response of 30/70mV@100mA/µs, and recovery time of 2µs without external capacitors. Compared with the prior art, this work achieves the best transient FOM of 12.19fs.

It is a challenge to implement a loss-of-signal (LOS) circuit with a wide threshold voltage range that is insensitive to temperature. This paper presents a new wide-range threshold-programmable LOS detector with full temperature compensation for application in 25Gb/s high-speed optical communication receivers. The wide-range programmable threshold voltage of the LOS detector is achieved by adjusting the threshold voltage of the peak detector and the gain of the variable gain amplifier (VGA). The detection accuracy is obviously improved by using offset self-cancellation technology for the comparator (COMP) and temperature compensation technology for the VGA and the peak detector. The LOS detector has been fabricated in 0.18 um BICMOS process and occupies 0.03mm². The programmable threshold voltage range is 11∼130mV for the 25Gb/s non-return-to-zero code, the hysteresis is 2dB, and the max detection error is 4mV. The LOS detector consumes 2.18mW from 1.8V supply voltage.

Wordline (WL) voltage-generating system is a crucial block in flash memory. It generates a voltage higher than the supply voltage for reading, programming and erasing in flash memory. However, operation accuracy is deteriorated by the excessive overshoot and ripple voltage. Moreover, current consumption in standby mode shortens the life of memory. The paper presents a high-performance wordline voltage-generating system in 55nm CMOS technology. In active mode, a variable stage and frequency charge pump system is proposed to suppress overshoot and ripple of WL voltage (V_WL) when the supply voltage ranges from 1.5V to 2.1V. To cut down standby current, an ultra-low power voltage reference circuit operating in subthreshold region is introduced. When recovering from standby mode, a standby recovery management circuit is utilized to minimize WL voltage setup time. The ripple voltage is 3mV at 30pF load with 20MHz pumping frequency in active mode in post-simulation. The WL voltage setup time when recovery from standby mode is equal to 13.7ns, even though the average standby current is less than 0.98µA typically.

A methodology for designing multioctave high-efficiency power amplifiers (PA) is presented in this letter. The sequential load-pull technique (SLPT) considering the second and third harmonic characteristics is proposed and combined with the multiple frequency matching theory (MFMT) to achieve outstanding performance in terms of operating bandwidth as well as efficiency. To verify the proposed theory, a 10 W GaN HEMT device is used. The proposed PA achieves a fractional bandwidth of 152% from 0.6 to 4.5GHz. In such a wide frequency band, the drain efficiency (DE) is measured as 50%-68% with an output power of greater than 38dBm and a large signal gain greater than 8dB.

We previously proposed the circular defect in two-dimensional photonic crystal (CirD) laser based on a GaAs/AlGaAs multilayer wafer, which is fabricated by dry etching. This CirD laser uses InAs quantum dot (QD) layers as the gain medium, but this inhibits vertical dry etching. We improved the dry etching process by introducing three QD layers and three-step dry etching for fabricating the CirD laser. As a result, CirD structures with good etching profiles could be fabricated and excellent optical properties were obtained. We observed lasing by a CirD laser fabricated by deep etching under photoexcitation measurement for the first time.