High-frequency circuit simulation in X-band coupled-cavity TWT

A study of the electrical performances of AlInN/GaN High Electron Mobility Transistors (HEMTs) on SiC substrates is presented in this paper. Four different wafers with different technological and epitaxial processes were characterized. Thanks to intensive characterizations as pulsed-IV, [S]-parameters, and load-pull measurements from S to Ku bands, it is demonstrated here that AlInN/GaN HEMTs show excellent power performances and constitute a particularly interesting alternative to AlGaN/GaN HEMTs, especially for high-frequency applications beyond the X band. The measured transistors with 250 nm gate lengths from different wafers delivered in continuous wave (cw): 10.8 W/mm with 60% associated power added efficiency (PAE) at 3,5 GHz, 6.6 W/mm with 39% associated PAE at 10.24 GHz, and 4.2 W/mm with 43% associated PAE at 18 GHz.

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Design of an X-band ridge-loaded staggered single-slot rectangular coupled-cavity traveling-wave tube

2014 IEEE International Conference on Communiction Problem-solving ◽

10.1109/iccps.2014.7062290 ◽

2014 ◽

Author(s):

Li Zhan ◽

Lingna Yue ◽

Sheng He ◽

Yanyu Wei ◽

Wenxiang Wang ◽

...

Keyword(s):

Traveling Wave ◽

Traveling Wave Tube ◽

Wave Tube ◽

X Band ◽

Coupled Cavity

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An Improved Equivalent Circuit Simulation of High Frequency Ultrasound Transducer

Frontiers in Materials ◽

10.3389/fmats.2021.663109 ◽

2021 ◽

Vol 8 ◽

Author(s):

Zhitian Shen ◽

Jie Xu ◽

Zhangjian Li ◽

Youwei Chen ◽

Yaoyao Cui ◽

...

Keyword(s):

Equivalent Circuit ◽

High Frequency ◽

Circuit Simulation ◽

Simulation Software ◽

Ultrasound Transducer ◽

Ultrasound Transducers ◽

High Frequency Ultrasound ◽

Matching Layer ◽

Backing Layer ◽

Frequency Ultrasound

The equivalent circuit simulation plays an important role in the design of ultrasound transducer. However, the existing methods are difficult to achieve the effect of matching and backing layer, and not able to accurately simulate the transducer with cable. Especially in the application of high frequency ultrasound, the long cable has a great influence on the performance of the transducer. To overcome these limitations, this paper proposed an improved equivalent circuit method, which combined Leach model and transmission line model. It can realize the complete simulation of ultrasound transducer with a long cable, matching layer, and backing layer in PSPICE circuit simulation software when the parameters were measured. Its principles were briefly introduced, and ultrasound transducers with different frequencies (12 and 20 MHz), different matching layers, and different cable lengths (0.5–2.5 m) were designed and fabricated to verify the effectiveness of the method, which is also compared with the traditional KLM method using PiezoCAD. The experiment results showed that the long cable, matching layer, and backing layer have a significant impact on the performance of high frequency ultrasound transducers, and this proposed method has good agreement with these results. Moreover, for the simulation of the complete transducer, the effect of this method is better than KLM model. Besides, this method does not need to know the specific equivalent circuit of matching, backing layer, or cable wire, it can accurately predict the impedance and phase of the transducer through the material parameters, which is very helpful for the material selection and optimization of subsequent transducer design and fabrication. The study indicates that this improved equivalent circuit method is suitable to be applied in the general circuit simulation software and provides strong support for the high frequency transducer and system design.

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