This paper proposes a MOSFET-only voltage reference using the standard 1.2-V MOSFET based on the 65nm CMOS technology, which achieves a power supply voltage operating range of 0.65 V to 2.5 V and the line regulation is 443μV/V. This work demonstrates the technique to achieve a low temperature coefficient and the function of offset voltage cancellation by ZTC-MOS, therefore, the effects of the offset voltage are eliminated. Monte Carlo simulation verifications were conducted based on the TSMC CMOS 65-nm process. Within the temperature range of -40 °C to 150 °C, the voltage reference is 507.4 mV and the temperature coefficient is 23.88ppm/°C in a 160-run Monte Carlo simulation. The overall power consumption is only 6.825 μW at 0.65 V supply under the TT corner and the temperature is set in the typical 27°C.

The rising demand for WAN capacity driven by the rapid growth of inter-data center traffic poses new challenges for costly optical networks. Today cloud providers rely on fixed optical backbones, where all hardware devices operate on a rigid spectrum grid, leading to the waste of expensive optical resources and subpar performance in handling failures. In this paper, we introduce FlexWAN, a novel flexible WAN infrastructure designed to provision cost-effective WAN capacity while ensuring resilience to optical failures. FlexWAN achieves this by incorporating spacing-variable hardware at the optical layer, enabling the generated wavelength to optimize the utilization of limited spectrum resources for the WAN capacity. The configuration of spacing-variable hardware in a multi-vendor optical backbone presents challenges related to spectrum management. To address this, FlexWAN leverages a centralized controller to achieve coordinated control of network-wide optical devices in a vendor-agnostic manner. Moreover, the flexibility at the optical layer introduces new algorithmic problems. FlexWAN formulates the problem of provisioning WAN capacity with the goal of minimizing hardware costs. We evaluate the system performance in production and share insights from years of production experience. Compared to existing optical backbones, FlexWAN can save at least 57% of transponders and reduce 36% of spectrum usage while continuing to meet up to 8× the present-day demands using existing hardware and fiber deployments. FlexWAN further incorporates failure resilience that revives 15% more bandwidth capacity in the overloaded optical backbone.

Because of the different working principles between conventional flyback and active-clamped flyback (ACF), the existing primary-side regulation (PSR) technology cannot be applied to ACF. And in order to achieve PSR of ACF, a low-cost digital sampling method based on the auxiliary winding of the transformer is proposed. In the conventional peak current mode (PCM) controlled ACF, the sampling resistor of primary current may introduce additional power loss, and high-frequency oscillations during sampling may reduce system's stability. Therefore, a digital feedback-feedforward control (FFC) method is proposed to eliminate the sampling resistor. The stability of the proposed control method and its influence on the dynamic response are studied. In addition, since GaN device has higher power loss during reverse conduction than its Si counterpart, design considerations of reverse conduction time of power switches are also discussed in this paper. All control methods and design considerations are verified on a GaN-based 12V-3A ACF, and the proposed control strategy is implemented by FPGA.

In the conventional peak current controlled active-clamped flyback converter, the primary side current sampling resistor Rsbrings many problems, among which the additional power consumption and instability are the most obvious ones. A new peak current control method without sampling resistor is proposed, which is suitable for both analog control (based on Analog IC or discrete components) and digital control (based on FPGA, ASIC, MCU, DSP, etc.). To exemplify, the FPGA-based digital control method is taken as case study, and the proposed control method is verified by experimental results. In a GaN-based 12V-3A ACF, the average efficiency is improved by upto 2.92% compared to the conventional peak current control methods. In addition, the dynamic response is greatly improved, and analysis is given to explain this improvement.

A novel robust watermarking algorithm based on the second-LSB (least significant bit) is proposed. The algorithm first groups the data by the hash value of the primary key and positions with the second-LSB of the data in every group. The watermark is not directly embedded in one single item, but one bit is embedded into one group by setting a pseudo-random number to the LSB of the data. A threshold, which is used for detection to be compared with the occurrence frequency of LSB positioned in embedding, and set according to the distribution probabilities of the data. Without affecting the usability of the data, the watermark is scattered in the databases evenly and hard to be detected. What's more, it keeps the distribution of the data. Experiments have shown that the algorithm is robust against various forms of attacks.

Wireless sensor networks are self-organized and data-centric. Security is a critical issue in many applications. In order to protect the security of data, we propose a novel secure transmission strategy based on information hiding (IH). In this design, we acquire sensitive information securely so as to make use of the advantage of IH technique without encryption. Our approach deal with the weakness of limitation in sensor node resources and the security threats, it is suitable for stream data in sensor nodes. The simulation experiments also demonstrate that this approach is effective in transmitting sensitive data covertly with the characteristics of lower energy consumptions and invisibility.