327 / | HD | MISCELLANEOUS ACTIVE ELECTRICAL NONLINEAR DEVICES, CIRCUITS, AND SYSTEMS |
524 | DF | SPECIFIC IDENTIFIABLE DEVICE, CIRCUIT, OR SYSTEM {22} |
530 | DF | .~ With specific source of supply or bias voltage {9} |
545 | DF | .~.~ Including signal protection or bias preservation {1} |
546 | .~.~.~ With field-effect transistor |