消除低频不稳是利用雪崩管设计毫米波固态源,特别是大功率源的重要课题.本文设计了一种新型的可调谐式低通阻抗变换器以消除振荡源的低频不稳定性.该变换器不仅能大大地抑制低频不稳,而且由它提供的调谐自由度,加上可移动的短路活塞提供的另一调谐自由度可使振荡源调至最佳状态.本文借助计算机对该变换器进行优化设计,并给出其带通特性的理论曲线. Eliminating low-frequency instability is an important issue to design a millimeter-wave solid-state source, especially a high-power source, using an avalanche tube.This paper designs a new tunable low-pass impedance converter to eliminate the low-frequency instability of the oscillation source. Not only can greatly suppress the low-frequency instability, but also it provides the tuning degree of freedom, coupled with the movable short-circuit piston provides another degree of freedom tuning can make the oscillation source to the best condition.In this paper, Optimize the design, and give the theoretical curve of its band-pass characteristics.