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Millimicrosecond Transistor Current Switching Techniques
| Content Provider | Semantic Scholar |
|---|---|
| Author | Et, H. S. Y. O. U. R. K. |
| Copyright Year | 2009 |
| Abstract | T HERE ARE five major limitations on the speed of transistor switching circuits. These are: 1) carrier storage delays, where the transistors are operated in saturation, 2) the limitations imposed by transistor and circuit capacitances, 3) a cutoff frequency, 4) diffusion or transit-time delay, 5) storage time in associated diodes. If transistor switching circuits are to have response times limited primarily by the bandwidths of the transistors operating as amplifiers and by diffusion or transit-time delay, it is necessary to avoid operation in saturation. As low collector-to-base voltage generally has a detrimental effect on transistor bandwidth, it is desirable, as well, to avoid operation near saturation. Where nonsaturating circuits are used, and when transistors having cutoff frequenceis of several hundred megacycles are considered, circuit capacitances become the primary limitation on speed. If we assume a current step into a node, where there is capacitance to ground a t the node, the voltage rise time is proportional to the required voltage swing. Therefore, to minimize the effects of circuit and transistor capacitances it is desirable to operate with voltage swings as small as reliability considerations will permit. A new mode of operation has been developed whereby well-specified currents can be switched reliably with small voltage swings. Transistors are operated well out of saturation, and switching speeds approach that of a grounded-base amplifier driven by a current step. The resulting logical circuits reset their own lev~ls. The circuits place no requirement on the upper limit of a and have a dc stability factor of unity. They have complemented outputs and provide an essentially constant load to all dc power supplies. The circuits are simple and relatively noise free. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://csdl.computer.org/csdl/proceedings/afips/1957/5050/00/50500068.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
