8542.39.00.20 - Active filters

This category, "Active filters," encompasses electronic integrated circuits specifically designed to perform filtering operations. Unlike passive filters which rely on discrete components like resistors, capacitors, and inductors, active filters incorporate active components such as operational amplifiers or transistors. These active components allow for amplification and gain within the filter circuit, enabling characteristics such as sharper cutoff frequencies, steeper roll-offs, and the ability to implement complex filter designs that are not feasible with passive components alone. They are essential for signal conditioning, noise reduction, and frequency selection in a wide array of electronic devices.

When classifying within the "Other" subcategory of electronic integrated circuits, it is important to distinguish "Active filters" from its sibling categories. For instance, "RF transceivers" are integrated circuits designed for both transmitting and receiving radio frequency signals, a function distinct from filtering. Similarly, "Data converters" are specifically for analog-to-digital or digital-to-analog conversion. The "Active filters" classification is for circuits whose primary function is to selectively pass or attenuate signals based on frequency, not for those with core communication or conversion functionalities, even if filtering is a secondary aspect of those devices. The catch-all "Other" categories (8542.39.00.70 and 8542.39.00.90) are to be considered only if the integrated circuit does not fit the specific descriptions of active filters, RF transceivers, or data converters.

As a leaf node, this classification does not have further subcategories. Therefore, the focus for classification here is on definitively identifying integrated circuits whose primary purpose and design are to function as active filters. This includes, but is not limited to, low-pass, high-pass, band-pass, and band-stop filters built around active electronic components for signal frequency manipulation. If an integrated circuit performs filtering as a secondary function alongside a primary function like signal amplification or signal processing, its classification would depend on the principal purpose of the circuit as a whole, potentially leading it to a different HTS code.