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# Mosfet Transconductance

47 Threads found on edaboard.com: Mosfet Transconductance

## AC Mains mosfet switch

hello, do you think my 2 mosfet AC switch is OK? it is for switch out inrush resistor in

## MOSFET scaling effects

Hai I want to know which are the capacitances that wll be effected by scaling of a transister.What are the new capacitances that will come into picture.

## What's the point of measuring Ft for MOSFET?

mosfet is voltage drive device, what's the point of measuring Ft? And what is the usage of Ft for mosfet?

## What is the difference between JFET and MOSFET?

The main different is that the JFET have a PN juntion for it have high input impedance. The mosfet have isolated gate with polysilicon.

## Questions about fMAX and fT of a MOSFET

I have a few questions about fMAX and fT of a mosfet: 1. What's the definitation of fMAX, the maximum oscillation frequency of a mosfet? 2. I remember the definition of cut-off frequency fT is the frequency when current gain Iout/Iin = 1. This gives out fT = gm/Cg. My question is: is transconductance gm a function of frequency? (...)

## Why variation of Gm in effective voltage is not considered in transconductance?

Mr.venkat3271 for ur kind information the drain current Id of a mosfet depends on the effective voltage.... please do refer some material on mosfet.....

## What is the effect when mosfet is on variable potential and W & L is varing?

mosfet Pdf file. You gothrough this file fully you can get an idea about your question

## Why MOSFET IS OPERATED in Saturation region.................

Why mosfet IS OPERATED in Saturation region in most of the analog applications? please explain with some references..

## uCox, GM and output parasitic capacitance for MOSFET

Please tell me 1.how to select ucox for a mosfet? Is it using tox?But is er and eo constant?wnt up and un gm(transconductance )for a particular technology viz., 0.35um ,fixed for a mosfet?if so, how do u find the value? 3.how to find output parasitic capacitance values for a cmos circuit

## Choosing Mosfets and mosfet-driver: Correctly done?

I'm new to mosfets and mosfet-drivers and would just like to check if I correctly determined the correct mosfet + driver to use using the correct calculations. Any criticism/suggestions are welcome. Thx in advance! mosfet: FDS6898A mosfet H-bridge Driver: MC33883

## What could affect MOSFET' s gate-souce break down voltage

Hi, All, I'm using a CMOS process, in which there are two types of NMOS devices with the same gate oxide thickness. But their gate-source break down voltages are different. Why it is like that? Thanks for any information.

## Transconductance VS Vgs in MOSFET

Hi, I am new to this filed on analog design. I am reading the book by Behzad Razavi on "Design of Analog CMOS Integradted Circuits" While reading on mosfets, I encountered an equation for transconductance which says that : gm = 2 * Id / Vgs - Vth .Its explanation states that Transcondutance decreses with overdrive (Vgs - Vth) when Id is co

## why fc does decrease with increasing R anymore

.i modify gate voltage to mos transistors,therewith the high mos resistance is controlled ,and the fc is further on controlled.:D Hi, In weak inversion the mosfet transconductance is given by "Id/nKT" i.e. independant of Vgs. So assuming you are using MOS as R or simillar to OTA-C implementation, the Res = 1/gm. So

## transconductance (u*Cox) parameter dependency to technology

hi Do you know the relationship between transconductance (u*Cox) parameter and technology? In other words how does change that parameter for a mosfet in .25 micron to 0.18micron? Regards

## which transistor provide more gain...Enhancement Mosfet or Depletion Mosfet?

which transistor provide more gain...Enhancement mosfet or Depletion mosfet? Please explain with solid reasons.... :) :)

## question about nonlinear model of MOSFET

Hi below image show the Simple CS transistor model with the transconductance nonlinearity and output conductance below equation is KCL at drain , I cant understand 4th part of this equation, please explain me how it dr

## Plotting Gm-transconductance of a MOS in LTSPICE

Hi! I need to plot transconductance(gm) of a mosfet(NMOS) in LTSPICE. Any idea how to do it? I am using TSMC 0.18um technology file. Also I need to observe gm upto 5 figures of precision. Please help me with that too... Right now I can view gm using dc operating point (.op) and going to Menu Bar->View->Spice Error Log (screenshot attached) and

## How to plot fT of MOSFET on cadence..?

How would you like to define a mosfet's small signal input current? Igs = Vgs * 2πf*Cgs ? Not too meaningful, I fear!

## Isolate or not? Balanced audio line with 100 drivers

OTA -> Operational transconductance Amplifier. An OPAMP is Voltage Controlled Voltage Source thus u can not connect output of them together but the output of VCCS (Voltage Controled Current Source) can be connected together, cos if the input voltage of any of them is zero, then the output is open circuit. u can use a simple jfet, mosfet or even a

## in Hspice , what is "beta"??

I designed simple Cs amp wit active load. follow is list file --------------------------------------------- element 0:mm1 0:mm2 0:m1 model 0:pch.13 0:pch.13 0:nch.18 region Saturati Linear Saturati id -1.5309m -1.4281m 1.4280m ibs 1.205e-20 1.125e-20 -2.331e-20 ibd 2.

## Meaning of 90nm,130nm,150nm etc.,

It is the gate length of the FET. effective length of the distance in the near-surface region of Si substrate between edges of the drain and source regions in the field effect transistor (including mosfet and CMOS). Reducing gate length is an effective way of reducing the transconductance of the channel. This implies that switchin

## questions on analog study

I agree with the above post. The major difference in the bipolar and the mos models is that between the Gate and other terminals, there is an open connection, while in a bipolar, there is a base resistance rb which will connect it to the collector terminal. Capacitances like Cπ and C? are replaced by CGS and CGD. So, the small signal modelling

## What is constant Gm biasing?

it's the equivalent of using a delta-vbe (ptat current) for biasing an op amp. basically your bias changes with temp inversely proportional to the diff pair, so you can keep the transconductance (and therfore GBW) constant over temp. now your room temp compensation *should* work over all temps. it's a good idea for any diff pair actually since i

## How to get the values defined in BSIM3 directly from Hspice?

You can simulate a single transistor in Hspice and get almost every model parameters. command .OP and DC sweep will do this job. For example, wanna get Ueff(effective mobility) of M1, just use: .probe dc ubeff(M1). Also gmo(m1) means transconductance of m1, vdsat(m1) is ..., I think you should know this : ) Sometimes maybe you don't know how to n

## does body effect limits the number of transistors?

as far as i thought ,,body effects makes the threshold voltage of mosfet changes,,,so,,you must care when placing the mosfets in series that they still operate in saturation region and this depend to a great extend on the supply voltage ;as it shrinks down ,placing mosfets in series becomes more difficult check this also

## Using multiplication factor 100 in current mirrors

With your questions, I noticed a discrepancy in my original post: The transconductance of Q2 should be 370uMhos. The transconductances that I presented were not really calculated from any real transistor sizes or process, just a guess for a starting point. The noise current in a mosfet is sqrt((8/3)*K*T*Gm), in amps/sqrt(frequency). (...)

## The output resistance of CMOS?

To measure it experimentally you can obtain the waveforms of the voltage and current on the output and then divide them with an digital oscilloscope, and with a single mosfet you can assume that the output resistance is the drain resistancei you look it from the drain and the inverse of the transconductance if you look it from the source.

## design issue about CML/SCL level shift

The reason you need the level shift in the bipolar design is to keep Q5 & Q6 out of saturation. Without the level shift the potential on the base of Q5 & Q6 will be too high which will lead to forward biasing the collector-base junction (saturation) of these transistors. This will kill your beta, Ft, thus the ac performance of these transistors.

## Unsymmetric differential amplifier

hi! unsymmetric input diff pairs cause mismatch to your diff stage. if you notice you have a "tail" to control the current flowing through both pairs, ideally you have identical sizes so same currents flow through them. since current is proportional to W/L in a mosfet, diff W/L ratios mean different current through your transistors. usually gain

## ONO layer in making PIP capacitor

In CMOS Process, ONO layer is known as reoxidized nitrided oxide. This layer was repleaced with SiO2, especially gate oxide of mosfet. it is said that Deep submicron mosfet with ONO gate dielectrics was superior to the mosfet with SiO2. The reasons are, 1. have improved saturation transconductance ( Frankly, I (...)

## current limit question in current mode buck converter ?

The simple way is to have resistor series connected to the inductor, or power mosfet. Then you can detect the voltage drop on this resistor and convert this voltage drop into current with V-I converter.

## "urgent" for design gm-c filter

hi i need to simulate "second-order Gm-C bandpass filter" with 10.7MHZ center frequency that its schematic is below.its structure is nauta transconductance.the reference journal is attached. i need help for simulate this filter by HSPICE software and 0.35um cmos standard parameters. it is not any problem to design this filter with c

## "urgent" for design gm-c filter

hi i need to simulate "second-order Gm-C bandpass filter" with 10.7MHZ center frequency that its schematic is below.its structure is nauta transconductance.the reference journal is HERE: i need help for simulate this filter by HSPICE software and 0.35um cmos standard parameters.

## Why 'gate width' is important?

Hi!Why 'gate width' is important in amplifier or mosfet? large gate width or small gate width which is good and why? THS! -CQCQ

## How to plot OP parameter with sweep variable in Spectre?

Hello everyone, I am confused how can i plot the operation point parameters with sweep variable in Spectre? For example, how to plot transconductance of a mosfet versus Vgs? Thank you so much!

## how to calaculate IGBT "ON Resistance"

Hi everybody, How to calculate IGBT "ON Resistance". I am using SGP23N60UFD in my design. In mosfet parameter(Rdson) is there for "ON Resistance". In SGP23N60UFD data sheet no where such parameter is not mentioned. Regards V. Naresh Kumar

## How to get the curve of gate capitance in ADS

Set "DevOpPtLevel" as "Brief" or "Detailed" in DC Analysis Setting parameters. See the followings. DC operating point data is generated for this model. If a DC simulation is performed,

## How to calculate the biasing voltages of conventional folded cascode amplifier?

please tell me how to calculate the biasing voltages of conventional folded cascode amplifier.. i am attaching my circuits.. also tell me how to calculate the device sizes of mosfets... please reply.....

## IIP3 and 1db compression point(P1dB) of LNA

P1dB is measured at output and not at input? P1dB - at output measured - should be proportional to P-DC. If this is not the case your mosfet goes into voltage saturation or current saturation and not both simultaneously. This is due to output mismatch.

## Design procedure for two stage opam(gm/id)

Hey, I see many posts on design of two stage opam.But honestly,I don't know where to begin and everything is seeming vague.I wrote the equations(transfer function)of a two stage opam from the equivalent circuit.Now i don't understand a few basic things >>Is the equivalent circuit representing two opams a combination of a few mosfets or two single

## Simple linear regulator question

Yes, you are right, the voltage variation is lower in the shown current range. I came to the same conclusion when checking the results. This is because you have selected a mosfet with a large Idss and respective transconductance. For a real voltage regulator, you would also want a tightly tolerated output voltage, which gonna be more problematic.

## Si & metal gate - performance differences

With metal gate you have a single work function and have to tune the body to get VT. With poly gates the doping could be (but was not necessarily) another degree of freedom; I saw in-situ-doped and S/D-doped processes. But the real benefit of poly gates was the self-aligned mosfet where poly defines the channel sharply. All of our old

## gm measurement plot in OTA in CADENCE 6.1.4

Hi Rajeshree; Well u can refer the tutorial on plotting the gm of the circuit in cadence. Hope this helps u. Muffassir

## is it varying Emitter - collector resistance according with base volt ?

YES, you can use a scope as a curve tracer to measure the current gain in a transistor or the voltage gain in a FET or the transconductance of a mosfet. Simply use series resistor on emitter to monitor current and display as Channel 1 and Voltage as Channel 2 and use scope in XY mode to see the input versus output. Remember transistors are curr

## Explain NMOS ID vs VDS curve graph

if you regulate the VDS > Vg-Vth then you are adding drain resistance (xΩ load vs 0Ω shunt) If saturated then then you get the green line.