A microwave comb generator based on AlGaN/GaN heterostructure Schottky diodes nonlinear transmission line

Abstract

In this paper, a microwave nonlinear transmission line (NLTL) based on AlGaN/GaN Schottky-barrier diodes (SBDs) is demonstrated. As a comb generator, the NLTL produces a frequency comb from 5 GHz to 40 GHz at the input frequency of 5 GHz. The output power at 35 GHz and 40 GHz are -14 dBm and -20 dBm at the input power of 22.5 dBm, respectively, which is superior to commercial GaAs NLTL. The NLTL is confirmed to have a higher saturation input power than commercial GaAs NLTL, indicating that the AlGaN/GaN NLTL is more advantageous at high power input.

A high-RF-bandwidth, high-IF-bandwidth monolithic terahertz heterodyne receiver based on AlGaN/GaN nonlinear transmission lines as a local oscillator and mixer

“…Twenty-nine pairs of AlGaN/GaN Schottky barrier diodes (SBDs) are periodically loaded into the coplanar waveguide (CPW) and form the NLTL. To obtain a broadband frequency comb as the LO source, the NLTL frequency comb generator is designed with three sections, 33) and the distances (d) between AlGaN/GaN SBDs from section#1 to section#3 are 600 μm, 300 μm and 150 μm, respectively. The characteristic impedance (Z p ) of the CPW at the input port of the NLTL is 50 Ω.…”

“…Thus, future work should focus on improving the sensitivity of NLTL heterodyne receivers, which can be realized through the following means. Firstly, increasing the input power of the microwave signal to enhance the power of the frequency combs, as referred to in our previous work, 33) will improve the sensitivity of the NLTL heterodyne receiver. Secondly, optimizing the structure of the AlGaN/GaN SBD to decrease the series resistance can reduce the loss of the frequency comb, increase the power of the LO frequency comb, reduce the loss of the IF signal, etc, and finally improve the sensitivity of the NLTL heterodyne receiver.…”