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Simplified cross section of a planar NPN bipolar junction transistor. BJTs consists of three differently doped semiconductor regions: the emitter region, the base region and the collector region. These regions are, respectively, p type, n type and p type in a PNP transistor, and n type, p type and n type in an NPN transistor.
For an NPN open emitter output, the collector is connected to the positive voltage rail, so the emitter outputs a high voltage when the transistor is on and is hi-Z when off. For a PNP open emitter output, the collector is connected to the low voltage supply, so the emitter outputs a low voltage when the transistor is on and is hi-Z when off.
Efficiency is mediocre because single npn-type transistors or Darlington pairs require fairly a high collector-emitter voltage drop. [28] 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]
Figure 3: PNP version of the emitter-follower circuit, all polarities are reversed. A small voltage change on the input terminal will be replicated at the output (depending slightly on the transistor's gain and the value of the load resistance; see gain formula below). This circuit is useful because it has a large input impedance
Thus for example a NPN gate driven by a PNP gate would see the threshold voltage of -6V in the middle of the range of 0V to -12V. Similarly for the PNP gate switching at 0V driven by a range of 6V to -6V. The 1401 used germanium transistors and diodes in its basic gates. [7] The 1401 also added an inductor in series with R2.
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 ...
Crankshaft position sensor (CKP) Curb feeler; Defect detector; Engine coolant temperature sensor; Hall effect sensor; Wheel speed sensor; Airbag sensors; Automatic transmission speed sensor; Brake fluid pressure sensor; Camshaft position sensor (CMP) Cylinder Head Temperature gauge; Engine crankcase pressure sensor; Exhaust gas temperature ...
Alternately, if a germanium PNP device was used, it would have significantly different characteristics than the silicon NPN transistor. In the quasi-complementary topology, the performance of the lower pull pair, which uses a single NPN transistor, more closely matches the performance of the upper push pair, which consists of two NPN ...