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This letter presents an approach to design the fourth-harmonic mixer based on a pair of antiparallel Schottky diodes. To implement the proposed fourth-harmonic mixer, a two-level local oscillator (LO) low-pass filter is used to suppress the second, third, and fourth harmonics of the LO frequency, further to improve the isolation between RF and LO ports. Also, two shorted grounds are adopted to ensure the wideband performance of the proposed mixer. Furthermore, a wideband fourth-harmonic operating at 325–500 GHz is fabricated and measured. The results show that it has very low conversion loss from 15 to 22 dB in the whole operational band.

A study on the damage effect of a GaAs pseudomorphic high-electron-mobility transistor (pHEMT) low-noise amplifier (LNA) induced by a Ku-band microwave is presented in this paper based on an experiment and simulation study. The experimental results suggest that the burn-out in the first stage is responsible for the LNA damage. Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS) were used to observe the damage situation and compare the element composition before and after the high power microwave (HPM) injection. It is found that the gate metal is melted as a result of heat generation. The location beneath the gate near the source side is badly burned and splashes out. A detail simulation is performed by establishing a two-dimensional electric-thermal model considering several physical models and thermal parameters using the simulator Sentaurus-TCAD. The results show that the burn-out location is consistent with the experiment findings. Meanwhile, a temperature elevation occurs in both the positive and negative half cycles. Moreover, the damage to pHEMT shows the working voltage dependence, and the burn-out time increases with the increase in drain voltage.

2D-mesh is widely used in Network-on-Chip as its regular topology and simple layout match the two-dimensional VLSI layout well. Further more, the optical circuit switching (OCS) is introduced to provide higher bandwidth and lower power consumption. However, the undesirable property of OCS is the coarse granularity of resource reservation. It leads to a high blocking ratio and degrades the performance. This paper proposes a multi-wavelength communication strategy and an optical router to solve this problem. The simulation results show that the strategy improves the performance in terms of end-to-end delay and throughput.