Fet Definition and 29 Threads

Homework Statement [Taken from Razavi's Design of Analog CMOS Integrated Circuits 2nd edition]Homework EquationsThe Attempt at a Solution [/B] I'm not too sure what to do with this question. Here's what I think of the circuit This doesn't look like a differential amplifier to me since...

Hello. I use 2 GaAs fet in a HF system. This assembly worked properly for several weeks and now doesn't work anymore. Before replacing these 2 transistors I would like to know how it is possible that all voltages ( drains & sources) are still correct, while the complete assembly stopped to work ?

Hey guys, I'm confused as to the difference between the h-parameters usually given by datasheets and their hybrid-pi model analogues. For instance, I know hfe = Beta in small signal analysis, but what about the other h-parameters. Thanks for any help with clarifying this.

1) When a FET is completely on, the voltage drop across the drain-source is ideally 0. This means that when completely on, V_{ds}<V_{gs}. Why doesn't the FET go into ohmic/triode mode when V_{ds} dips below V_{gs} ? 2) Why are we measuring these voltages relative to the source (for a standard...

The Drive terminals are connected to a PWM signal generated by an arduino micro controller. The purpose of this circuit is to isolate the arduino from the motors to avoid too much current being drawn. What I understand so far: The motor will only turn when the diode is reverse biased. When it...

Homework Statement I am trying to analyze the following circuit: "Note that if the two 2N5485s approximately match in their characteristics, not only is the voltage gain unity, but the DC offset is small: the constant current due to Q2 creates a constant voltage drop across R1. Furthermore...

why are people saying BJTs are cheaper to OPERATE? the field effect devices require less current and should therefore cost less no?

BJT ,the output voltage is amplified because there is dc voltage supply to keep BJT active ,but what about the FET? The voltage supplied only control the gate only, anything to do with the output? Thanks

Homework Statement I'm given this configuration with a AC source at v_{i} with a R_{sig} connect to the source before the capacitor. R_{sig} = 0.6 KΩ R_{G} = 1 MΩ R_{D} = 2.7 KΩ R_{L} = 4.7 KΩ I_{DSS} = 10 mA v_{p} = -6 V Homework Equations The Attempt at a Solution...

Homework Statement Find the voltage gain A_{v} http://imageshack.com/a/img692/3117/qkwp.png Homework Equations The Attempt at a Solution Is this the correct small signal equivalent? http://imageshack.com/a/img203/5812/1yfe.png I'm trying to find the output impedance...

Hi everyone, I have attached an image of fet amplifier in common source configuration. I want to have the ac analysis of this circuit. I am able to figure out the input impedance and the voltage gain. But I can't formulate for output impedance. According to me, while calculating output...

How to design a Output enable ckt (like the ones in logic gates and buffers) using a simple component like BJT or FET.

I want to drive a IRFP250N power MOSFET using a square wave generated by an Arduino at high frequencies, maybe 1kHz or so. I doubt I can hook up the digital out to the mosfet gate, so is there some kind of gate driver I can make/buy that will take in the square wave signal and violently switch...

Fresh EE here that hasn't seemed to cover the main application of either a BJT or mosfet. When should you use one in place of the other? There doesn't seem to be a clear distinction between the two, however I would imagine there are substantional practical differences. Situation in...

Hello all, In one of our labs we determined the input impedance of a FET amplifier circuit via a potentiometer. We were told it was due to "maximum power transfer theorem" (something we have not learned yet). Essentially we attached a potentiometer in series with the input of the circuit and...

i don't understand how an applied Voltage on a (intrinsic) Carbon Nanotube could change its conductance... There is not a population inversion like in mosfet. So, which is the physics? Where this carriers can from? thank you.

Hi, I've been busy in designing some circuits and I want to simulate some non linear behavior of transistors and diode circuits. I want to find a free simulation program. Does LT Spice work on these discrete components? Thanks Alan

Hi, I fabricated a very simple back-gate FET. I used highly Boron doped (so, P-type) Si wafer as a gate and then, grown SiO2 thermally as a dielectric. And, deposited N-type semiconductor followed by Au/Cr deposition as electrodes (source and drain). And I measured Ids-Vds and Ids-Vg. The...

I am designing a circuit to control an LED. The current will be under 40mA and the 2n7000 FET has a maximum operating current of 200mA continuous. See attached schematic. The switch in my final circuit is actually another IC. I looked up the http://www.fairchildsemi.com/ds/2N%2F2N7000.pdf"...

Hi guys, can anyone tell me the reason why we set Vi=0 (short circuit the input side) when we want to find the output impedance Zo but we don't do the same by setting Vo=0 when we find the input impedance Zi? and why do we let Io=0 (open circuit the output side) to find the gain Av? thank you

I'm a little outside my area of expertise here - I've used ADS to exhaustion, but now I need to simulate a MESFET I designed. Anyone have any recommendations for software? Our computer labs have quite a bit, but if there's a nice free/lite version that would be ideal. Thanks in advance.

Homework Statement A BJT has VA of 50 V and MOSFET has lambda(modulation length) = .02 V^-1, and has VGS-VTN=.5 What are the "amplification factors" of the 2 transistors. Homework Equations well, not sure, all i really want to know is what do they mean by amplification factors...

A bit awkward question but still it confuses me... A BJT is a current controlled device because its output characteristics are determined by the input current. A FET is voltage controlled device because its output characteristics are determined by the Field which depends on Voltage applied...

Hi everyone, Just wondering if anyone in the forum have any experience in carbon nanotube field-effect transistor biosensor? I have a real head ache on how to overcome non-specific binding in this device. And I am wondering if someone would be kind enough to give some suggestions...

Hi! I am learning this topic of the electronics and they say that "for an n-channel Junction FET, gate current is to be avoided; consequently the gate-channel junction is never foward biased". My question is why that gate current has to be avoided?

Hi, just logged on first time in ages. Got a message saying that my password was 563 days old lol. Right now, I'm in first year of uni so very stupid :smile: Anyways, we're studying about field-effect transistors. I understand how the gate controls the current via adjusting the size of the...

I came across a schematic of a buffer amplifier utilizing a p-channel fet as input. It is from a sweep oscillator generating a ramp voltage by charging C3 and C4 with a constant current, (current source is not shown, Q2 just acts as a switch or buffer). Now as the voltage rises linearly across...

Hi guys! can anybody suggest me any link from where i can get a detailed understanding of large signal operations of MOSFETs? Thanks in advance

Hi, I have a question pertianing to the effect of capacitance of BJT amplifier circuits on the low and high frequency response of the amplifier. Why is it that the coupling and the decoupling capacitors, in effect, only affects the low frequency response of the amplifier, and why is it...