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Bipolar Junction Transistors
- current controlled
- use both holes and electrons as carriers
- have three terminals called the emitter, base, and collector
- only available in one mode of operation
Field-Effect Transistors
- voltage controlled (like vacuum tubes)
- use either holes or electrons as carriers, not both
- have three or four terminals called the source, gate, drain and sometimes substrate
- available in either enhancement mode or depletion mode of operation
What else can I help you with?
What is the PIV rating of transistor?
The PIV (Peak Inverse Voltage) rating of a transistor, particularly in the context of bipolar junction transistors (BJTs) and diodes, refers to the maximum reverse voltage that the device can withstand without breaking down. For BJTs, the PIV is typically related to the collector-emitter voltage (V_CE) in reverse bias conditions. Exceeding the PIV rating can lead to failure or damage of the transistor, so it is crucial to operate within specified limits to ensure reliability and longevity.
Why current gain is important parameter in bjt where as conductance is important in fet?
Current gain in bipolar junction transistors (BJTs) is crucial because it indicates the amplification capability of the device, determining how much the input current can control the output current. In contrast, conductance is a key parameter for field-effect transistors (FETs) since it reflects how well the device can conduct current in response to an applied voltage, emphasizing its voltage-controlled nature. Thus, BJTs are current-controlled devices while FETs are voltage-controlled, making these parameters critical to their respective operation and applications.
What are the normal operating condition of transistor?
The normal operating conditions of a transistor typically involve it being in one of its active regions, such as the active region for bipolar junction transistors (BJTs) or the saturation region for field-effect transistors (FETs). For BJTs, this means the base-emitter junction is forward-biased while the collector-base junction is reverse-biased. For FETs, it involves applying a sufficient gate-source voltage to allow current to flow between the drain and source. Under these conditions, the transistor can amplify signals or switch them effectively.
Is the common source amplifier is out of phase?
Yes, the common source amplifier is out of phase. It inverts the input signal, meaning that when the input voltage increases, the output voltage decreases, and vice versa. This phase shift is a characteristic feature of common source configurations in field-effect transistors (FETs) and bipolar junction transistors (BJTs).
How many kinds of emitter?
There are primarily two types of emitters: current emitters and voltage emitters. Current emitters provide a constant current output, while voltage emitters maintain a constant voltage. Additionally, in the context of semiconductor devices, there are specific types such as bipolar junction transistors (BJTs) and field-effect transistors (FETs) that have their own emitter configurations. Each emitter type serves different applications in electronic circuits.
What are the main differences between FETs and BJTs in terms of input impedance?
FET has very high input impedanceBJT has very low input impedance
What is the PIV rating of transistor?
The PIV (Peak Inverse Voltage) rating of a transistor, particularly in the context of bipolar junction transistors (BJTs) and diodes, refers to the maximum reverse voltage that the device can withstand without breaking down. For BJTs, the PIV is typically related to the collector-emitter voltage (V_CE) in reverse bias conditions. Exceeding the PIV rating can lead to failure or damage of the transistor, so it is crucial to operate within specified limits to ensure reliability and longevity.
Is the collector current dependent on colllector- emitter voltage in BJTs?
No. For BJTs, they have a natural amplification, B, of current between the base current to collector current. In rough calculations, I've often used 50. So applying 20uA of current to the base of a BJT should cause 1mA of current to flow through the collector (assuming base, collector, and emitter resistors are sized appropriately so this is not limitted). The emitter will see the base current + the collector current.
Why current gain is important parameter in bjt where as conductance is important in fet?
Current gain in bipolar junction transistors (BJTs) is crucial because it indicates the amplification capability of the device, determining how much the input current can control the output current. In contrast, conductance is a key parameter for field-effect transistors (FETs) since it reflects how well the device can conduct current in response to an applied voltage, emphasizing its voltage-controlled nature. Thus, BJTs are current-controlled devices while FETs are voltage-controlled, making these parameters critical to their respective operation and applications.
What are the normal operating condition of transistor?
The normal operating conditions of a transistor typically involve it being in one of its active regions, such as the active region for bipolar junction transistors (BJTs) or the saturation region for field-effect transistors (FETs). For BJTs, this means the base-emitter junction is forward-biased while the collector-base junction is reverse-biased. For FETs, it involves applying a sufficient gate-source voltage to allow current to flow between the drain and source. Under these conditions, the transistor can amplify signals or switch them effectively.
Is the common source amplifier is out of phase?
Yes, the common source amplifier is out of phase. It inverts the input signal, meaning that when the input voltage increases, the output voltage decreases, and vice versa. This phase shift is a characteristic feature of common source configurations in field-effect transistors (FETs) and bipolar junction transistors (BJTs).
How many kinds of emitter?
There are primarily two types of emitters: current emitters and voltage emitters. Current emitters provide a constant current output, while voltage emitters maintain a constant voltage. Additionally, in the context of semiconductor devices, there are specific types such as bipolar junction transistors (BJTs) and field-effect transistors (FETs) that have their own emitter configurations. Each emitter type serves different applications in electronic circuits.
Why bandwidth of fet is larger than bjt?
The bandwidth of a Field-Effect Transistor (FET) is generally larger than that of a Bipolar Junction Transistor (BJT) due to the differences in their operating principles. FETs operate using electric fields to control current, leading to lower capacitance and faster switching speeds. In contrast, BJTs rely on charge carrier injection and recombination, which introduces delays that limit their frequency response. As a result, FETs can achieve higher frequency operation and greater bandwidth compared to BJTs.
What is TTL logic?
TTL Logic Circuits - "Transistor Transistor Logic" - are made using BJTs. They operate from +5 Volts. These are available from simple AND, OR, NAND Gates to complex circuits. The voltage levels are INPUT OUTPUT Low (0) < 0.8V <0.4V High (1) >2.0V >2.4V Levels in between are undefined. The outputs are better than the inputs by 0.4V thus offering a noise margin. These are seldom used these days as other logic families have been introduced offering more advantages like, speed, lower power, wider / lower operating voltage, higher fanouts.
What is a variable transistor?
A variable transistor is a type of transistor whose characteristics can be adjusted, typically to control the flow of current or voltage in a circuit. This adjustment can be achieved through various means, such as changing gate voltage in field-effect transistors (FETs) or altering the biasing conditions in bipolar junction transistors (BJTs). Variable transistors are often used in applications like amplifiers, oscillators, and signal modulation, allowing for dynamic control over electronic signals.
What are the two main types of transistors?
The two main types of transistors are bipolar junction transistors (BJTs) and field-effect transistors (FETs). BJTs operate by controlling the flow of current via two types - NPN and PNP. FETs control current flow using an electrical field, with types including MOSFETs and JFETs.
What jobs can a transistor do when combined with the CPU?
The modern CPU (typically inside a microprocessor IC) is built of billions of transistors (typically complementary MOSFETs). The CPUs of the late 1960s were built of tens of thousands to hundreds of thousands of transistors inside several hundred MSI ICs (typical silicon NPN BJTs). The CPUs of the late 1950s to early 1960s were built of thousands to tens of thousands of discrete transistors (typically germanium BJTs, gradually transitioning silicon BJTs). The CPUs of the early 1950s did not use transistors, they were built of hundreds to tens of thousands of vacuum tubes.
