番茄花园-ElectronicCircuitsandApplications-资料
合集下载
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
A control element is a network element that can be used for the control of power flow. A control element normally requires at least three electrical terminals, with the v-i characteristic at the output terminal pair being dependent on the voltage or current at the other terminals. The transform is a control element.
3.0 Active devices and Control Elements (1)
1. What is an active device有源器件? An active device is a device capable of controlling the flow of
electrical energy from a source to a load. If an active device is to be useful for increasing the power level of signal, then the power required at the control inputs must be much less than the power delivered to the load, the balance coming from the dc power sources. The combination of the active device and its associated power source then functions as an amplifier, and is said to have power gain. The opamp is an active device. 2. What is a control element控制器件?
Contents Previous Return Next End
3.1 Bipolar Transistors as Control Elements (1)
3.1.1 The Physical Basis of Transistor Operation
Injection注入, Diffusion扩散, and Collection收集 A typical bipolar transistor structure is shown as
Contents Previous Return Next End
3.0 Active devices and Control Elements (2)
3. Transistor and classification The transistor is made from semiconductor. It is the most
Contents Previous Return Next End
3.1 Bipolar Transistors as Control Elements (5)
Contents Previous Return Next End
3.1 Bipolar Transistors as Control Elements (6)
Contents Previous Return Next End
3.1 Bipolar Transistors as Control Elements (2)
To understand how the bipolar transistor operates as a control element, we can draw on our understanding of the p-n junction diode developed in Section 7.3. In the diode a forward bias produces a significant current resulting from a net flow of holes and electrons from the regions where they are majority carriers to the region where they are minority carriers. This injection process is reviewed schematically in following figure.
Electronic Circuits and Applications
Chapter Three Physical Electronics Of Transistors
2019/8/9
Contents Previous Return Next End
Chapter Three Physical Electronics Of Transistors
3.1 Bipolar Transistors as Control Elements (4)
In the normal gain or the active gain region放大区 of operation, the emitter-base junction is maintained in forward bias, and the collector-base junction is held in reverse bias. By doping the emitter region much more heavily than the base, most of the injection of minority carriers is made to occur into the base side of the junction. Thus, under forward bias conditions, there is a large buildup of minority carriers ( electrons in an NPN transistor, holes in a PNP transistor) on the base side of the emitter-base junction. While this buildup of electron concentration is taking place at the emitter end of the base region, the reverse-biased collector-base junction keeps the concentration of minority electrons very low at the collector end of the base region. This combination of a forward bias at the emitter-base junction and a reverse bias at the collector-base junction thus establishes a large concentration gradient of minority carriers across the base region. Normal thermal motions, therefore, produce a diffusive flow of minority electrons through the base region, from the emitter end, where they are in excess, to the collector end, where they are swept across the collector-base junction into the collector region.
The bipolar transistor works as a control element by combining injection at one of its p-n junctions with collection at the other p-n junction.
Contents Previous Return Next End
It consists of a p-type central region, called the base基区, which is sandwiched between two n-type regions, called the emitter发射区 and the collector集电区. This arrangement is known as an NPN transistor. It is also possible to construct a complementary form, the PNP transistor, by using p-type material for the emitter and collector regions and n-type material for the base. In either case, the bipolar transistor consists of two p-n junctions that share a common region, the base, between them.
Contents
Active devices and Control Elements Bipolar Transistors as Control Elements Field-Effect Transistors as Control Elements
Contents Previous Return Next End
widely used active device in modern electronic circuits. Transistors can be divided into tBiblioteka Baiduo general categories:
Bipolar transistor (BJT) 双极性晶体管 Field-effect transistor (FET) 场效应晶体管
3.1 Bipolar Transistors as Control Elements (3)
Under reverse bias, the p-n junction diode is characterized by a small saturation current, arising from the collection of minority carriers from their respective regions by the electric field in the space-charge layer. The magnitude of this reverse saturation current depends on the available concentration of minority carriers, and is small in the diode.
The total terminal current I is given by the sum of the two current components arising from the hole flow and the electron flow.
Contents Previous Return Next End
3.0 Active devices and Control Elements (1)
1. What is an active device有源器件? An active device is a device capable of controlling the flow of
electrical energy from a source to a load. If an active device is to be useful for increasing the power level of signal, then the power required at the control inputs must be much less than the power delivered to the load, the balance coming from the dc power sources. The combination of the active device and its associated power source then functions as an amplifier, and is said to have power gain. The opamp is an active device. 2. What is a control element控制器件?
Contents Previous Return Next End
3.1 Bipolar Transistors as Control Elements (1)
3.1.1 The Physical Basis of Transistor Operation
Injection注入, Diffusion扩散, and Collection收集 A typical bipolar transistor structure is shown as
Contents Previous Return Next End
3.0 Active devices and Control Elements (2)
3. Transistor and classification The transistor is made from semiconductor. It is the most
Contents Previous Return Next End
3.1 Bipolar Transistors as Control Elements (5)
Contents Previous Return Next End
3.1 Bipolar Transistors as Control Elements (6)
Contents Previous Return Next End
3.1 Bipolar Transistors as Control Elements (2)
To understand how the bipolar transistor operates as a control element, we can draw on our understanding of the p-n junction diode developed in Section 7.3. In the diode a forward bias produces a significant current resulting from a net flow of holes and electrons from the regions where they are majority carriers to the region where they are minority carriers. This injection process is reviewed schematically in following figure.
Electronic Circuits and Applications
Chapter Three Physical Electronics Of Transistors
2019/8/9
Contents Previous Return Next End
Chapter Three Physical Electronics Of Transistors
3.1 Bipolar Transistors as Control Elements (4)
In the normal gain or the active gain region放大区 of operation, the emitter-base junction is maintained in forward bias, and the collector-base junction is held in reverse bias. By doping the emitter region much more heavily than the base, most of the injection of minority carriers is made to occur into the base side of the junction. Thus, under forward bias conditions, there is a large buildup of minority carriers ( electrons in an NPN transistor, holes in a PNP transistor) on the base side of the emitter-base junction. While this buildup of electron concentration is taking place at the emitter end of the base region, the reverse-biased collector-base junction keeps the concentration of minority electrons very low at the collector end of the base region. This combination of a forward bias at the emitter-base junction and a reverse bias at the collector-base junction thus establishes a large concentration gradient of minority carriers across the base region. Normal thermal motions, therefore, produce a diffusive flow of minority electrons through the base region, from the emitter end, where they are in excess, to the collector end, where they are swept across the collector-base junction into the collector region.
The bipolar transistor works as a control element by combining injection at one of its p-n junctions with collection at the other p-n junction.
Contents Previous Return Next End
It consists of a p-type central region, called the base基区, which is sandwiched between two n-type regions, called the emitter发射区 and the collector集电区. This arrangement is known as an NPN transistor. It is also possible to construct a complementary form, the PNP transistor, by using p-type material for the emitter and collector regions and n-type material for the base. In either case, the bipolar transistor consists of two p-n junctions that share a common region, the base, between them.
Contents
Active devices and Control Elements Bipolar Transistors as Control Elements Field-Effect Transistors as Control Elements
Contents Previous Return Next End
widely used active device in modern electronic circuits. Transistors can be divided into tBiblioteka Baiduo general categories:
Bipolar transistor (BJT) 双极性晶体管 Field-effect transistor (FET) 场效应晶体管
3.1 Bipolar Transistors as Control Elements (3)
Under reverse bias, the p-n junction diode is characterized by a small saturation current, arising from the collection of minority carriers from their respective regions by the electric field in the space-charge layer. The magnitude of this reverse saturation current depends on the available concentration of minority carriers, and is small in the diode.
The total terminal current I is given by the sum of the two current components arising from the hole flow and the electron flow.
Contents Previous Return Next End