In electronics, a cut-off is a state of negligible conduction which is a property of several types of electronic components when a control parameter (which usually is a well-defined voltage or electric current, but could also be an incident light intensity or a magnetic field), is lowered or increased past a value (the conduction threshold). The transition from normal conduction to cut-off can be more or less sharp, depending on the type of device considered, and also the speed of this transition varies considerably.
- Silicon diode: cutoff occurs when Vf falls below apx 0.7 V. The exact voltage varies with temperature.
- Germanium diode: apx 0.3 V, varying with temperature
- Schottky diode:
- Zener diode: reverse cutoff defined by diode voltage rating. Forward cutoff apx 0.6 V.
- Thermionic diode: cutoff voltage depends on device design. Much higher than for silicon devices.
- Copper oxide diode:
- Selenium diode:
- Silicon transistor: apx 0.6 V, varying with temperature.
- Germanium transistor: apx 0.2 V, varying with temperature
- Triodes: triodes cut off when applied grid bias is too low. This will be a negative voltage under ordinary conditions.
- Tetrode, Pentode etc.: There is some degree of interaction between the grids, and values will vary from one device to another. Anode voltage also affects cutoff voltage.
- Electrical conduction
- Electronic component
- Field effect transistor in JFET and MOSFET form
- Vacuum tube
- Explanation of remote-cutoff control grids in vacuum tubes.
- Explanation of sharp-cutoff control grids in vacuum tubes.
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