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A typical use of these transistors is as a switch for moderate voltages and currents, including as drivers for small lamps, motors, and relays. [1] In switching circuits, these FETs can be used much like bipolar junction transistors, but have some advantages: high input impedance of the insulated gate means almost no gate current is required
PMOS transistors operate by creating an inversion layer in an n-type transistor body. This inversion layer, called the p-channel, can conduct holes between p-type "source" and "drain" terminals. The p-channel is created by applying a negative voltage (-25V was common [ 18 ] ) to the third terminal, called the gate.
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 ]
The high power consumption of ECL meant that it has been used mainly when high speed is a vital requirement. Older high-end mainframe computers, such as the Enterprise System/9000 members of IBM's ESA/390 computer family, used ECL, [26] as did the Cray-1; [27] and first-generation Amdahl mainframes. (Current IBM mainframes use CMOS. [28])
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. This kind of amplifier can enhance ...
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 ...
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.