A 200-GHz GaN-Based Frequency Doubler With Bidirectional Electro-Thermal Coupling Method

In this letter, a bidirectional electro-thermal coupling (BETC) method is proposed to design high-efficiency terahertz (THz) frequency doubler. The effect of temperature on diode characteristics and metal conductivity is taken into consideration in circuit design. Moreover, the electromagnetic loss of the frequency doubler is reduced by multiple bidirectional coupling iterative optimization to improve conversion efficiency. For demonstration, a THz frequency doubler was designed with a balanced structure and assembled with a flip-chip configuration. Under the continuous wave (CW) mode excitation of 500 mW, a peak conversion efficiency of 13.2% is obtained at 200 GHz with output power of 66 mW, which further confirms the advancement of the BETC method.