Фізична еквівалентна схема інжекційно-прольотного транзистора в режимі прямого зміщення емітерного переходу

Abstract

На основі розглянутої структури інжекційно-прольотного транзистора розроблено його фізичну еквівалентну схему, описано принцип її роботи, теоретично обгрунтовано коефіцієнт передавання по струму еквівалентної схеми та зроблено експериментальну перевірку коректності отриманих результатів.

Injection-span transistor (IST) occupies an intermediate position between bipolar and field effect transistors. The structure is similar to unijunction transistor (UT) and field-effect transistors with p-n junction. According to the principle of operation it is close to the bipolar transistor because of using injection properties of a directly biased p-n junction and two types of charge carriers - electrons and holes. However, unlike these devices under forward biased emitter junction there are falling areas in its current-voltage characteristics, where the Ohm's law is disrupted, so that it has a negative differential resistance, which relates it to R - type negatron. These properties determine the broad functionality of IST in various electronic devices. Designed unijunction transistors have low operating frequencies (several hundred kilohertz). This is a disadvantage of those transistors and limits the range of their applications, mostly as low-current keys. Progress in the development of microelectronic technologies allows to overcome this disadvantage, extending the frequency range of up to several gigahertz, and makes the task to design various analog electronic circuits based on IST. A necessary condition for such devices design is a presence of physical equivalent circuit of IST, which describes the parameters with sufficient accuracy in a wide frequency range. When designing the key circuits in low-frequency range a one-diode physical equivalent circuit of unijunction transistor received an application, which ignores span effects in the base and therefore can’t be used in the design of devices based on IPT. Therefore, we solve the problem of IST physical equivalent circuit design, which considers its reinforcing properties and frequency dependence of its parameters in active mode. On the basis of the injection-span transistor structure, its physical equivalent circuit was developed and the principle of its operation was described. The current transfer coefficient of the equivalent circuit was theoretically grounded and experimental verification of the results correctness was conducted. Physical equivalent circuit of IST considers its general properties of bipolar and field effect transistors. Frequency dependence of the parameters is taken into account by the IST emitter junction capacity and the time of the main charge carriers flight through the channel. At higher frequencies it is necessary to bring interelectrode capacitances and inductance pins in the physical equivalent circuit. To improve the accuracy of calculations of electronic devices based on IST it is necessary to develop methods for experimental determination of its physical equivalent circuit parameters.