0
What else can I help you with?
What is the effect of Rs and RL on the voltage gain of an amplifier?
it reduces the gain
Why to calculate the current gain in transistor?
A: Transistors are really voltage amplifiers since the effect is voltage across a load. Using beta as a means to calculate gain is an approximation. basically is the ratio emitter resistor and collector resistor with no loadNo. Transistors (bipolar junction types, what most people think of as "transistor") are considered to be current devices.Although it's possible to specify a transconductance (output current/input voltage), this has not been done since the earliest days of transistor theory, and you will have trouble actually finding a transconductance specification in data sheets.Current gain is (output current/input current).In a common emitter circuit, this is (collector current/base current), known as hfe or "beta", with ranges from as low as 10 for high-current devices to high hundreds for low-power audio types.In common base, it's (collector current/emitter current), and it's just a bit less than 1.0, typically 0.95 to 0.999. This is known as hfb or "alpha".In common collector, it's (base current/emitter current), known as hfc, with about the same values as hfe.The exceptions are the obsolete point-contact types of the 1950s/early 1960s, and the various types of field-effect/MOS devices known variously as FETs, JFETs, IGFETs and MOSFETs.The field-effect/MOS devices have very low/zero input current, so they are not specified for current gains.
What is difference between early effect and punch through in BJT?
When we apply reverse bias voltage to input and output sides of a BJT, then the width of the depletion layer at emitter-base and base-collection got increased. Due to which the effective base width got decreased. This phenomenon of reduction in the base width is called Early effect. And if we go on increasing the Reverse bias voltage then at a time instant the width of the base becomes zero and this effect is called punch through effect and that reverse bias voltage is called punch through voltage.
How does a jfet input operational amplifier work?
A: an operational amplifier has two input A+ and a - input feeding to a base of a transistor ideally both diodes are matched with a current source to make them equal so basically they are both balanced or virtually at the same potential increasing one potential to one will inversely effect the other. usually these junctions are transistor base to emitter but it could that one is just a plain diode working on the exponential curve of the diodes
What effect does low impedance have on voltage regulation?
raised voltage output
What is the effect of no emitter resistance on common emitter amplifier?
Limit current through emitter, Often the resistance is the load itself. So the restatnce limits current on what otherwise would act as a voltage follower.
What is the effect of emitter resistance in common emitter amplifier?
The gain of a common-emitter amplifier is collector resistor divided by emitter resistor, or hFe, whichever is less. Since hFe depends on temperature, designing the amplifier to be dependent on resistance ratio makes it more stable. As such, the emitter resistance serves to stabilize the amplifier.
What is the effect on voltage gain in a common emitter amplifier when the decoupling capacitor is removed?
The emitter bypass capacitor, in a typical common emitter configuration, increases gain as a function of frequency, making a high pass filter. Removing the capacitor will remove the gain component due to frequency, and the amplifier will degrade to its DC characteristics.
What is effect of an unbypassed resistor on the common emitter amplifier circuit?
An emitter resistor in a common emitter circuit will cause the stage to experience the effects of degenerative feedback if it is unbypassed. The degenerative feedback reduces gain. This is probably the primary effect in the described circuit.
When emitter resistors is bypassed with a capacitor how is the gain of the amplifier affected?
Bypassing the emitter resistor with a capacitor in an amplifier configuration effectively removes the negative feedback provided by the resistor at high frequencies. This results in an increase in voltage gain, as the gain is primarily determined by the ratio of the collector and emitter resistances. However, the capacitor only provides this effect at certain frequencies, allowing for improved gain without affecting low-frequency stability. Thus, the overall gain of the amplifier increases at higher frequencies while maintaining lower frequency performance.
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).
What is the effect of Rs and RL on the voltage gain of an amplifier?
it reduces the gain
What is common emitter amplifier with degeneration?
In electronics, a common-emitter amplifier is one of three basic single-stage bipolar-junction-transistor (BJT) amplifier topologies, typically used as a voltage amplifier. In this circuit the base terminal of the transistor serves as the input, the collector is the output, and the emitter is common to both, hence its name. An analogous circuit called the common source is constructed using field-effect transistors Common-emitter amplifiers generally have a very high gain which can vary widely from one transistor to the next, as it is a strong function of both temperature and bias current, making the actual gain unpredictable. Stability is another problem associated with such high gain circuits, due to any unintentional positive feedback that may be present. Other problems associated with the circuit are the low input dynamic range imposed by the small-signal limit and the high distortion resulting if this is exceeded. One common way of alleviating these issues is with the use of negative feedback, particularly with emitter degeneration. Emitter degeneration typically refers to the addition of a small resistor (or any impedance) between the emitter of the transistor and ground. The effect of this is to reduce the overall transconductance Gm = gm of the circuit by a factor of gmRE + 1, making the voltage gain depend more on the ratio of the resistors than the transistor's characteristics: The distortion and stability characteristics of the circuit are thus improved, but at the expense of a reduction in gain. Common-emitter circuits are used to amplify weak voltage signals, such as the faint radio signals detected by an antenna. When used in radio frequency circuits, it is common to replace the load resistor with a tuned circuit. This is done to limit the bandwidth to a narrow band centered around the intended operating frequency. More importantly it also allows the circuit to operate at higher frequencies as the tuned circuit can be used to resonate any inter-electrode and stray capacitances, which normally limit the frequency response. Common emitters are also commonly used as low noise amplifiers. At low frequencies and using a simplified Hybrid-Pi model, the following small signal characteristics can be derived. If the emitter degeneration resistor is not present, RE = 0 Ω. According to these formulas and in agreement with the previous discussion, when RE is increased the input resistance is increased and the gain is reduced. {| ! ! Definition ! Expression ! Current gain ! Voltage gain ! Input resistance ! Output resistance |} The bandwidth of the common emitter amplifier tends to be low, due to high capacitance resulting from the Miller effect. The base-collector capacitance is effectively multiplied by the factor 1 − Av, thus increasing the total input capacitance and lowering the overall bandwidth. The discussion of bandwidth parallels that in the article on the common source amplifier. A fix for this bandwidth problem is the cascode amplifier. == ==
What is effect on amplifier output if you increase input impedence?
Impedence is synonymous with resistense. Greater the I, lesser the outputNo.First, it's *resistance* and *impedance*.Now, if the amplifier is a current amplifier, the above makes sense. (higher Zin, less Iin for a constant Vin).But if it's a purely voltage amplifier, it only responds to the input voltage, so the impedance (so long as it's not affecting the source/driving device) will have no effect on a purely voltage-amplifying amplifier.
What is the effect in an input impedance of a common emitter amplifier if the bypass capacitor is removed?
The input impedance of a common emitter amplifier is hfe (or beta) times the sum of the emitter resistance, re = kT/qIc, plus the external impedance in series with the emitter. k - Boltzmann's constant, T - degrees Kevin, q - electron charge, Ic - collector current makes the intrinsic emitter resistance about 26 ohms at 1 ma. If the bypass capacitor impedance is much less than 26 ohms at the frequency of interest, then for a beta = 100 transistor operating at 1ma the input impedance is about 2600 ohms at low frequencies ie. 100 * (26 + 0). Say the external emitter resistance is 1K ohm and you remove the bypass cap. The total emitter resistance is now 26+1000 or 1026 ohms and the input impedance is now 100 * (26+1K ohms) or 102.6K ohms.
Why a low value of load resistance has significant effect on the voltage gain of a common-source amplifier?
A low load resistance in a common-source amplifier can significantly reduce the overall voltage gain because it introduces a larger voltage drop across the load, decreasing the output voltage. The voltage gain (Av) is influenced by the load resistance (RL) since it is part of the voltage divider formed with the output resistance of the transistor. When RL is low, the effective output impedance decreases, leading to a lower gain. Additionally, a low load resistance can also increase the output current, potentially driving the amplifier into a nonlinear region, further affecting gain stability.
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.
