Bjt vs mosfet amplifier review
Try out PMC Labs and tell us what you think. Learn More. Field effect transistors FET have been widely used as transducers in electrochemical sensors for over 40 years. Measurements are performed on two chloride electrochemical sensors that are identical in all details except for the transducer device type. Comparative measurements show that the transducer choice significantly impacts the electrochemical sensor characteristics.
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What Is A Mosfet Amp?
Good input, Charles. Nelson has not found any problem, I suspect that it will take a more serious measurement technique in order to find what it does in that case. Attached Files f4 thd freq. Nelson, I am thinking of an asymmetrical pulse or something else, in order to bring out even more change. I know that a curve tracer shows big changes as well.
Hi Nelson, Quote:. Find More Posts by Bob Cordell. Hi, Mr. Hansen, Thanks for the enlightment The non-linearity of Cgd by varying Vds, in the case of near clipping where Vds approaching 0 , could this be countered by a low impedance drive powerfull VAS drive output? Find More Posts by lumanauw. Charles, just a quick one on your new amp: are those enclosures also milled from a solid chunk of aluminium?
Haven't read the article yet but the workmanship looks first class at the minimum! Jan Didden. Find More Posts by jan. BB code is On. Smilies are On. Forum Rules. All times are GMT. The time now is PM. Resources saved on this page: MySQL User Name. Stay logged in? Mark Forums Read. Solid State Talk all about solid state amplification.
Please consider donating to help us continue to serve you. Page of Last ». Thread Tools. Charles Hansen R. Join Date: May Location: Colorado. Quote: Originally posted by Bob Cordell I have usually not subscribed to the generalization of simpler is better, but I have also seen examples out there where added complexity has been foolish and possibly sound-degrading.
The key, I think, is the "right" degree of complexity for a given objective. Having had a background in linear IC design, I have usually not hesitated to add a transistor if it cleaned up a shortcoming in a another transistor in a straightforward way without introducing a gotcha. The Triple output stage is a good example of such straightforward and generally good circuit additions, in my opinion. Heck, let's face it, bypassing an electrolytic capacitor is also an example of increased complexity when you come right down to it if it is a given that one needed the electrolytic in the first place, of course.
Originally posted by Bob Cordell As I said, I think the use of the Triple concept with vertical MOSFETs completely eliminates the conern about the Cgd at least to the analogous point that it exists for bipolars as well in the same architecture , but I am very interested in learning of your other concerns with vertical MOSFETs that you have developed over the years, since discussion of those would be extremely relevant to this thread.
Although my designs tend to use global negative feedback, I think that any concerns that you developed in regard to vertical MOSFETs in your non-feedback architectures would in most cases be just as relevant to NFB amplifiers, since the goal for NFB amplifiers at least the one that should always be practiced is that the open loop should be as linear as possible BEFORE closing the loop. View Public Profile. Find More Posts by Charles Hansen. Send a private message to john curl. Find More Posts by john curl.
Quote: Originally posted by john curl Good input, Charles. Find More Posts by Nelson Pass. Hi Nelson, Quote: I have an example of a Class A complementary follower no loop where you can see the distortion vs frequency at 1 watt bump up from.
Send a private message to anatech. Find More Posts by anatech. Quote: Originally posted by Charles Hansen Since that time I have also found that simpler is not always better. In our latest amp the MX-R , the added transistors used to stabilize the operating point of the input FET which provides all of the gain improve both the sound and the measurements.
It's kind of interesting, really. The FET operates as a voltage-to-current converter, and then it has a load resistor that acts as a current-to-voltage converter. The whole system is so darned linear that it's kind of scary.
If we made a low-powered class-A amp with this circuit and avoided any problems with crossover distortion in the output stage , I think we could get the open-loop distortion down to around 0. Well, the two problems with vertical MOSFET's are a zero tempco point at one or two orders of magnitude higher than you would like, plus the non-linear Cgd.
In comparison, the only problem with the lateral is the lack of transconductance. But if you parallel a bunch of lateral devices, you can get as much transconductance as you want. The resultant composite device will be better than an equivalent vertical part in four ways: a The non-linearity in Cgd will be about an order of magnitude better. The only disadvantage is cost. But since we are talking about high-performance audio instead of mass-market audio, I see no reason to use vertical parts if you are going to use MOSFET's.
The one nice thing about MOSFET's versus bipolars is their relative immunity to instability when faced with a capacitive load. But in the end, I have come to prefer BJT's overall. As an aside, you should know that there is an inherent defect in the IR P-channel parts. The time scale in question is on the order of a few milliseconds, which puts the problem smack-dab in the audio band. If you search the archives, you will find some other posts I have written on this topic.
Send a private message to Bob Cordell. Send a private message to lumanauw. Visit lumanauw's homepage! Quote: Originally posted by lumanauw The non-linearity of Cgd by varying Vds, in the case of near clipping where Vds approaching 0 , could this be countered by a low impedance drive powerfull VAS drive output? Send a private message to jan. Quote: Originally posted by janneman Charles, just a quick one on your new amp: are those enclosures also milled from a solid chunk of aluminium?
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Difference between BJT and MOSFET
To enable the student to understand how transistors form key analog circuit building blocks — from single transistor amplifiers to OpAmps. Transistors circuit building blocks The key building blocks for transistor analog circuits including current mirrors, diode connected MOSFETs, Cascode circuits, active resistors, potential dividers, current mirrors. Operational Transconductance Amplifiers and the construction of Op-amps from individual transistors. Operational amplifier including summation, differencing, comparator, and integration circuits.
What’s the difference between MOSFET and BJT?
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BJT vs MOSFET
An amplifier is an electronics device which raises the strength of a weak signal. In our previous article we discussed how a transistor can function as an amplifier. But just like the BJT, it too needs to be biased around a centrally fixed Q-point. Since the source terminal is common to the input and output terminals, the circuit is called common source amplifier. The circuit is zero biased with an a.
MOSFET Amplifier
What about speed? If you are to build your own dream power amplifier, which would you choose as the driver stage device? For what reason? How about in the preamp or input stage of a power-amp? Some use JFETs.
Even though both of them are transistors, they are different from each other in various aspects. A Bipolar junction transistor, commonly known as BJT, by its construction, looks like two p-n junction diodes connected back to back. It is a three-terminal Emitter, Base, collector , current controlled device. In NPN transistors, a thin layer of p-type semiconductor is sandwiched between two n-type semiconductors whereas, in PNP transistors, a thin layer of n-type semiconductor is sandwiched between two p-type semiconductors.
If we asked most people about the purpose of the basilar membrane, we might receive answers ranging from something that protects a boat hull from leaking to something about strange lights in the night sky. In all seriousness though, the basilar membrane --in partnership with the cochlea and tiny hair cells--allows all of us--and all our fellow vertebrates--to hear or perceive sound. With one end stiff and narrow and other end wider and flexible, the basilar membrane becomes stimulated by sine waves. Each wave travels from the stiff, narrow end to the wider, flexible end, increases in amplitude, and then decreases in amplitude. As the vibrations vary in frequency, high frequencies produce peaks near the narrow end and low frequencies peak toward the wide end. While the basilar membrane performs as a frequency analyzer and frequency-tuned delay line, the cochlear mechanically amplifies the movement of the membrane.
The cascode is a two-stage amplifier that consists of a common-emitter stage feeding into a common-base stage. Compared to a single amplifier stage, this combination may have one or more of the following characteristics: higher input—output isolation, higher input impedance , high output impedance , higher bandwidth. In modern circuits, the cascode is often constructed from two transistors BJTs or FETs , with one operating as a common emitter or common source and the other as a common base or common gate. The cascode improves input—output isolation reduces reverse transmission , as there is no direct coupling from the output to input. This eliminates the Miller effect and thus contributes to a much higher bandwidth.
If you are exploring the world of electronics, and you want to know more about the Transistors and MOSFETs for your upcoming brilliant project, you are at the right place. Before semiconductors particularly transistors , the only devices available for signal amplification and switching were Vacuum Tubes. And when I say vacuum tubes, the first thing that comes to the mind is a big bulky device, inside which the vacuum tubes reside. They require a high operating voltage they eat a lot!
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