Electro-Thermal Design for Broadband Balanced Terahertz Tripler

This paper presents a comprehensive electro-thermal (E-T) design method applied to the circuit design of the multipliers, which intends to improve the design flexibility and simulation reliability of the broadband frequency multiplier.The design method is divided into two steps: a self-consistent electro-thermal model and an external matching circuit. The self-consistent electro-thermal model consists of three parts: the steady-state thermal model, the thermal separation variable model, and the three-dimensional (3-D) electromagnetic (EM) model. The electro-thermal model is suitable for application in hybrid integrated circuit, because the thermal correction is only carried in simulation. There is no additional diode and temperature-controlled equipment cost in thermal parameters extraction. Then, a formula-based impedances network named linear embedding impedances is set as external wideband response instead of single frequency point embedding impedance. This two-step design method enables the nonlinear I-V thermal correction, circuit matching design and their coupling simulation in circuit level. Based on the design approach, a balanced 225–300 GHz frequency tripler with AlN substrate has been designed and manufactured. The output consistency of simulated and measured results reachs up to 82% and the S11 basically better than -10 dB across the wideband of 225-300 GHz.