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In this paper, a zero-bias mixer using a lateral field-effect diode fabricated on standard GaN-on-Si AlGaN/GaN high electron-mobility-transistor wafers is demonstrated. The diode features strong nonlinearity near zero bias, enabled by a threshold-voltage modulation using a fluorine-plasma-treatment technique. The maximum change in conductance was adjusted to ~0 V, leading to optimal conversion loss (CL) of the mixer at zero bias and eliminating the need for any dc supplies. The mixer is characterized from room temperature (RT) to 250 °C. At 2.5 GHz and at RT, the CL and third-order intermodulation intercept point are 12.9 dB and 17.64 dBm, respectively. The operation of the proposed diode is modeled by a physical equivalent circuit, wit the element values extracted from the measured S-parameters. The voltage-biasing dependence of the CL can be explained by a the model. The high-temperature operation of the mixer shows that the proposed mixer can perform well in high-temperature and ultralow-power applications. [ABSTRACT FROM AUTHOR]

The finite-difference time-domain (FDTD) technique was extended to analyze the frequency response of surface acoustic wave (SAW) filters. In this method, the partial derivatives of quasi-static Maxwell's equations and the equation of motion are discretized to centered finite differences. In addition, the perfectly matched layer boundary condition was applied to reduce spurious reflections. Two structures are considered in this paper. First, the model was applied to analyze the influence of the number of electrodes on the frequency response of a SAW filter fabricated on a zinc oxide (ZnO) substrate. Then, the proposed method was further extended to analyze the frequency response of a ZnO/diamond/Si-layered SAW filter. The simulated results are in a good agreement with the existing experimental data, indicating that the FDTD method was an appropriate approach for modeling SAW devices. [ABSTRACT FROM AUTHOR]

We demonstrate a single-chip switch-mode boost converter that features a monolithically integrated lateral field- effect rectifier (L-FER) and a normally off transistor switch. The circuit was fabricated on a standard AIGaN/GaN HEMT epitaxial wafer grown with GaN-on-Si technology. The fabricated rectifier with a drift length of 15 μm exhibits a breakdown voltage of 470 V, a turn-on voltage of 0.58 V, and a specific on-resistance of 2.04 mΩ cm². The L-FER exhibits no reverse recovery cur- rent associated with the turn-off transient because of its unipolar nature. A prototype of GaN-based boost converter that includes monolithically integrated rectifiers and transistors is demonstrated using conventional GaN-on-Si wafers for the first time to prove the feasibility of the GaN-based power IC technology. [ABSTRACT FROM AUTHOR]