Transistor stacking is a promising technique to increase the working voltage and output power of power amplifiers (PAs). A DC negative feedback mechanism in stacked PAs is analyzed and verified through measurement in this paper. This negative feedback mechanism ensures the stability of stacked PAs at DC conditions. Based on the analysis of this mechanism, the DC biasing procedure of stacked PAs is also analyzed in this paper. Finally, an experiment is performed to verify our analysis. The results of this paper prove the feasibility and stability of the stacked PA.

In this brief, a wide stopband bandpass filter is designed based on the substrate integrated waveguide (SIW) coupling with complementary split ring resonators (CSRRs) and defect ground structure resonators. The proposed filter exhibits excellent roll-off and wide stopband characteristics with single SIW resonator cavity. A simple capacitive slot line is also proposed to improve the flatness in the passband. In order to verify the feasibility of this scheme, the filter is processed and measured. The measurement results show that the operating frequency band is 4.4GHz-5.0GHz which covers the N79 frequency band of 5G microwave communication with stopband range of 6.4GHz-21.6GHz.

The ToF system has a wide range of applications, including automatic driving, 3D reconstruction, and intelligent robot navigation, and more. However, implementing time-of-flight (ToF) systems for measuring real-time distances of objects with varying surface reflectance poses a challenge. The varying reflectivity of object surfaces results in fluctuations in the amplitude of the reflected pulse, causing the input overdrive voltage to the comparator to vary widely. It is a challenge to achieve low propagation delay with small input overdrive. To address this issue, this paper proposes a rail-to-rail high speed continuous time comparator with a new propagation delay optimization circuit. The circuit comprises an automatic clamp circuit and an improved class-AB stage with a clamping function, enabling faster charging and discharging of parasitic capacitances. As a result, the propagation delay for low input overdrive is reduced. The comparator was designed and simulated in 3.3V, 0.35µm CMOS process. The simulation results indicate a static power consumption of 10.56mW. For 5mV input overdrive, the maximum propagation delay is approximately 9.6ns.

Traditional backscatter enhancement devices include corner reflectors and Luneburg lenses. Corner reflectors are typically made of metal and consist of two or three angled surfaces, resulting in heavy weight and large volume. Luneburg lenses are made of dielectric materials and have higher costs. Both devices require a certain amount of space and are not easy to place. To address these issues, this paper presents a 1-bit 12×12 reconfigurable reflection array that can be attached to the surface of smooth objects. It operates in the frequency range of 10.5-11.5GHz and achieves full coverage of high-gain backscattering radar cross section (RCS) within the -45° to 45° angular range by changing the coding arrangement of the array. The 1-bit reconfigurable unit is composed of four basic units, with each unit having a PIN diode connecting two separate square metal plates on its surface. By controlling the on/off state of the PIN diodes, a phase difference of 180° in the reflected electromagnetic waves is achieved, enabling the 0/1 coding of the array. The combination of the deep deterministic policy gradient (DDPG) algorithm and electromagnetic simulation software is employed to search for coding schemes with high gain, directly evaluating the simulation environment helps to avoid errors that may arise from theoretical calculations and simulations. Simulation results show that, the designed metasurface achieves 5∼27dB RCS enhancement for y-polarized waves within the 90° angular range, demonstrating superior wide-angle RCS enhancement effects.

Electromagnetic interference has always been an important assessment indicator for the inspection of power intelligent Unmanned Aerial Vehicles (UAVs). Therefore, it is necessary to carry out a structure optimization study to improve the UAV’s anti-electromagnetic interference capability. This paper analyses the flight stability of the UAV at different heights under the strong magnetic environment of the dry-type transformer, and carries out structural optimisation of the rotary-wing UAV design against the standard non-magnetic environment. After simulation and comparison, the UAV’s anti-electromagnetic interference capability is significantly enhanced after structural optimisation. The research results of this paper can further expand the application scope of inspection UAVs and provide a strong technical guarantee for promoting the development of intelligent and automated power inspection.

Hybrid folded microstrip and slotline (HFMS) spoof surface plasmon polaritons (SSPPs) are developed to design a balanced bandpass filter (BPF). The proposed HFMS SSPPs can lower the upper cut-off frequency for size reduction of nearly 65%. Microstrip-to-slotline transition structure is adopted for feeding structure. Under differential mode (DM) operation, a band-pass response is formed by the high-pass microstrip-to-slotline transition structure and low-pass SSPP structure. Under common mode (CM) operation, high CM suppression is achieved due to intrinsic CM rejection ability of microstrip-to-slotline transition structure. Finally, a balanced BPF with compact size and high CM suppression is fabricated, and measured.

We present an area-efficient and low-power four-channel 25-Gb/s trans-impedance amplifier for an Rx analog front-end (Rx-AFE) on an optical receiver. The proposed circuit features a local negative-feedback trans-impedance amplifier (TIA) to expand the bandwidth. The TIA and post-amplifier use regulated cascode (RGC) topology and two differential amplifier stages with an inductive peaking bandwidth extension technique to acquire 19.6GHz of the -3dB bandwidth and 53.3dBΩ of the gain. We designed the system using a 65-nm CMOS process, and the proposed four-channel Rx-AFE TIAs achieved a small area of 300µm × 800µm per lane. From the measurement results, the differential output voltage was 160mV at 25-Gb/s PRBS31. The test chip has also 85.0mW of power consumption; hence, it achieves 0.85mW/Gb/s of power efficiency.

Hands are the most useful organ in our daily life while the monitoring of hand action still lacks report until now. The monitoring and analysis of human hands will benefit the development of medical science, automatic robots, and human action analysis. Here, we build a non-battery system to monitor human hands. The system is fixed on a glove with five flexible sensors on each tip of the finger to monitor the pressure on these positions and a hard in the center to collect power and drive the circuits. Furthermore, after the mechanical analysis, a specially designed S shape structure is used for the lines in this system to make it have more movement room and robustness. The final system is used in the monitoring of basketball games with the center part pad to collect the energy and the sensitivity of the sensor is measured as 0.04 V/N. Four actions on hand in a basketball game are measured and the pressure on four fingers is analyzed, showing the force distribution of each finger. This work demonstrates that the design can be used in the analysis of hand movement to make an innovation to the sensing of the human body.