0
To design a bjt amplifier with gain 10, consider that gain in a class A common emitter configuration is collector resistance divided by emitter resistance.
So, pick the two resistors so that their ratio is ten. Bias the base so that the collector is at the center of the operating voltage range, along with the transistor being at the center of its linear region.
Of course, you need to consider impedance and operating current, so you need to choose carefully. Also, the beta (hFe) of the transistor must be substantially more than ten for this to work reliably.
Often, this voltage gain stage is followed by a class C common collector emitter follower to give you current gain as well.
Wiki User
∙ 14y ago
Add your answer:
Earn +20 pts
How do you calculate the current gain of a transistor?
Bipolar transistor current gain is also called "Beta," or the h-parameter "hfe." beta = current_out / current_in The beta of a BJT is mostly determined by the thickness of the Base region, and by the excess doping in the Emitter relative to the Base. A thin Base and a heavily-doped Emitter leads to a high value for current gain. In a BJT, beta = Ic / Ib In a FET, beta is usually taken as infinity, since no current flows in or out of the gate. Beta is an impirical number. It means nothing unless the Ic is known or the load. It can have a beta from 1000 to 10 it all depends on the load.
What are the release dates for Design School - 2010 2010-10-29?
Design School - 2010 2010-10-29 was released on: USA: 29 October 2010
What are the release dates for The Nate Berkus Show - 2010 Nate's Design and Conquer Top 10 Tips?
The Nate Berkus Show - 2010 Nate's Design and Conquer Top 10 Tips was released on: USA: 1 June 2011
What are the release dates for Keyshawn Johnson Tackling Design - 2009 Robyn's Kitchen Reverse 1-10?
Keyshawn Johnson Tackling Design - 2009 Robyn's Kitchen Reverse 1-10 was released on: USA: 29 August 2009
What are the release dates for Find and Design - 2004 Carrie Riordan and Kyle Garlet?
Find and Design - 2004 Matt and Lynn was released on: USA: 10 November 2007
How emitter bypass resistor stabilizes the amplifier against temperature?
In the common emitter (Class A) amplifier design of a BJT, gain is collector resistance divided by emitter resistance, or hFe, whichever is less. If the emitter resistance is zero, then gain is hFe. In this configuration, gain is unstable, because hFe is temperature dependent. In fact, under certain circumstances, a BJT can experience thermal runaway. The emitter resistor (along with the collector resistor) places a limit on the expected gain of the stage. If, for example, you design with a ratio of 10, then you expect a gain of 10. If hFe is 25-100, gain is still 10.
What are the values so that over all gain is 10 in instrumentation amplifier?
You need a divider that is 10 to 1. You could use 10 megohms in the feedback and 1 megohm in the bottom leg. Since you are probably talking about an operational amplifier, you need this in both legs.
Why transformer is not called an amplifier?
In an ideal transformer the power in equals the power out there is no gain. In an ideal amplifier the power out equals the Gain *Power In. An ideal transformer transforms energy at a ratio of its windings. For example an ideal 1:10 ratio transformer (step up) would convert a 10Volt input at 10amps to a 100Volt output at 1Amp. Or conversely an ideal 10:1 ratio transformer (step down) would convert a 10Volt 10Amp input into a 1Volt 100Amp output. Since Power = Voltage * Current we can see the power in equals the power out in an ideal transformer. In an ideal amplifier the power out is greater than the power in. This is defined as the gain of the amplifier. An ideal amplifier with a Voltage gain of 10 would take a 1Volt 1amp signal and amplify it into a 10Volt 1 amp signal. An ideal amplifier with a Current gain of 10 would take a 1Volt 1Amp signal and amplify it into a 1Volt 10 amp signal. Since Power = Voltage * current we can see the power in is less than the power out showing a gain in power.
Why op amp circuit without negative feedback so unstable?
I f an amplifier has a great gain lets say 1000 and the power supply is 10 v then 10 mv will saturate the amplifier to either rail some amps has 10mv just in offset voltage
What is the meaning of gain in an amplifier or operational amplifier. Is high gain or low gain is what we try to achieved?
There are many uses for amplifiers. Some try to achieve extremely high gain such as in a radio receiver. Many try to achieve no overall gain. Examples include mixers and filters. Some only try to achieve limited gain. Oscillators try to achieve zero gain at most frequencies but unity to very high gain at the frequency of oscillation depending on the output wave form required. Basically - everything in electronics is an amplifier. The absolute gain of am amplifier is the ratio of output signal to input signal. For voltage or current amplifiers this is usually expressed as field decibels which is 20 log (out/in). For power amplifiers the gain in decibels is 10 log (output power/input power). If the gain is less than one, the same rules apply but the decibels will turn out to be a negative quantity.
What is voltage offset?
Input offset voltage is the equivalent voltage at the input of an operational amplifier. If an amplifier has a voltage gain of ten and an input offset voltage of 10 microvolts, a level of 100 microvolts will appear at the output with no input. Manufacturers try to design an op amp so the input offset voltage is as small as possible to minimize this error voltage at the output of the amplifier, especially for applications where small voltages are being amplified.
What is the HFE for good transistors?
A: HFE is meaning less uunless current is specified. For a switch force gain of 10 for an amplifier at low level maybe 100 for the same transistor.
How do you calculate the current gain of a transistor?
Bipolar transistor current gain is also called "Beta," or the h-parameter "hfe." beta = current_out / current_in The beta of a BJT is mostly determined by the thickness of the Base region, and by the excess doping in the Emitter relative to the Base. A thin Base and a heavily-doped Emitter leads to a high value for current gain. In a BJT, beta = Ic / Ib In a FET, beta is usually taken as infinity, since no current flows in or out of the gate. Beta is an impirical number. It means nothing unless the Ic is known or the load. It can have a beta from 1000 to 10 it all depends on the load.
Can you amplify DC voltages?
Yes, certainly - an operational amplifier circuit (see e.g. Wikipedia) will do this. For instance, a non-inverting amplifier circuit with a gain of 10 will give 1.0V output for 100mV input, 2.0V for 200mV, and so on (limited by the supply voltage of the amplifier). Physical sensors such as thermocouples or strain gauges often need DC amplification to make their outputs easier to measure.
What kind of amp do you need for one 10 inch Alpine Type X subwoofer?
Alpine offered up until last year the PDX-1000 wich is a 1000 Watts RMS amplifier designed with the type X subwoofer series in mind. Now the best match would be the PDX-M12. Set the amplifier gain carefully as this amplifier is a bit strong for this subwoofer.
Input impedance of voltage amplifier?
In audio the input impedance of an amplifier is between 10 kiloohms and 20 kiloohms.
Why you are more concentrated on gain-bandwidh product in amplifiers?
Amplifiers all have a gain bandwidth product that varies greatly from device to device. Obviously the bandwidth becomes important at very hi frequency. Is the gain enough for 100 megahertz for a gain of 10? if not you need another amplifier. also the bandwidth product is an indication of how close can one f/b without causing oscillations..
