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Diode–transistor logic (DTL) is a class of digital circuits that is the direct ancestor of transistor–transistor logic. It is called so because the logic gating functions AND and OR are performed by diode logic , while logical inversion (NOT) and amplification (providing signal restoration) is performed by a transistor (in contrast with ...
A single common-emitter pnp-type transistor can operate correctly in saturation mode, with only ≈0.25 V voltage drop, but also with impractically high base currents. [29] A compound pnp-type transistor does not need as much drive current, but it requires at least a 1 V voltage drop. [ 29 ]
A Class B push–pull output driver using a pair of complementary PNP and NPN bipolar junction transistors configured as emitter followers. A push–pull amplifier is a type of electronic circuit that uses a pair of active devices that alternately supply current to, or absorb current from, a connected load.
Some DTL designs used two power supplies with alternating layers of NPN and PNP transistors to increase the fan-out. Transistor–transistor logic (TTL) was a great improvement over these. In early devices, fan-out improved to 10, and later variations reliably achieved 20.
The output is usually connected to an external pull-up resistor, which pulls the output voltage to the resistor's supply voltage when the transistor is off. For PNP open collector outputs, the emitter of the PNP transistor is internally connected to the positive voltage rail, so the collector outputs a high voltage when the transistor is on or ...
In 1987, IBM released an update to the IBM PC known as the Personal System/2 line of computers using the Micro Channel Architecture. [12] The PS/2 was capable of totally automatic self-configuration. Every piece of expansion hardware was issued with a floppy disk containing a special file used to auto-configure the hardware to work with the ...
An IGBT cell is constructed similarly to an n-channel vertical-construction power MOSFET, except the n+ drain is replaced with a p+ collector layer, thus forming a vertical PNP bipolar junction transistor. This additional p+ region creates a cascade connection of a PNP bipolar junction transistor with the surface n-channel MOSFET. The whole ...
In the latest CMOS processes, β of vertical PNP transistors can even go below 1. To add to the design challenge, device properties often vary between each processed semiconductor wafer. Device properties can even vary significantly across each individual IC due to doping gradients. The underlying cause of this variability is that many ...