noun
filter; wave filter
Technical term for a device or circuit that passes or blocks signals based on frequency; used in electronics and signal processing.
この回路には高周波を除去するろ波器が組み込まれている。
This circuit incorporates a filter that removes high-frequency components.
ろ波器の設計には伝達関数の知識が必要だ。
Designing a filter requires knowledge of transfer functions.
フィルター is the common loanword for general filters (optical, coffee, etc.), while ろ波器 is a technical term specifically for electronic wave filters.
Compound of ろ (filter) and 波器 (wave device). The exact historical derivation is uncertain; the spelling is conventionally associated with electronic filtering.