"阶式滤波器" can be translated as "cascaded filter" or "staged filter" in English.
"Cascaded filter" is a more common term in technical contexts, referring to a filter configuration where multiple filter stages are connected in series, each contributing to the overall filtering effect.
"Staged filter" also conveys the idea of a filter composed of multiple stages, though it may be slightly less common in specific technical literature compared to "cascaded filter".
Both terms are appropriate, and the choice between them may depend on the specific context or preference of the speaker or writer.