Questions tagged [transconductance]

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31 questions
29 views

Plotting G(t) of an oscillator in Cadence

I have a cross-coupled NMOS-only oscillator that has its bias voltage changing so its transconductance is also changing over time. I want to plot its transconductance (G(t)=G0-gm/2) over time in ...
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Constant-gm bias circuit

I am doing a study on Improvements in biasing and compensation of CMOS opamp. Do you guys know how to come up with the equation for RDS4C ?
44 views

Error Amplifier Gain

I was studying the "SG3525" IC and its functions, and I encountered this issue: In the "Error Amplifier" section of the Datasheet, there is a parameter that named "DC trans-conductance" which it is "...
112 views

Measuring transconductance of any circuit

May I know if the following transconductance measurement test circuit is correct because I am getting quite small Gm values ? I suspect that I need to use some derivative function because changing ...
73 views

From here, it's said that a higher gm/Id results in lower current consumption (which is usually preferred in low power operation) But what other effects does a high gm/Id have? Will it have other ...
1k views

Understanding Operational Transconductance Amplifiers

I understand the high-level function of OTAs, that they provide an output current proportional to an input voltage. But what I don't understand, and what I can't seem to find any information on online,...
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OTA design, the Gm won't go down to zero

I'm trying to simulate a pseudo-differential OTA, but the the Gm vs Vin(differential) plot I obtain seems warped. The Gm won't go down to zero for large values of Vin. attached is the circuit ...
89 views

Determine transconductance of a JFET given only voltage gain and internal drain resistance

I have a homework question as follows: If a JFET having a specified value of rd=100 kΩ has an ideal voltage gain of Av(FET) = -200, what is the value of gm ? As far as I know, the closest formula for ...
873 views

Common Source JFET Amplifier Gain

I would be thankful if someone could explain me what is the general formula used to calculate the gain of a common source jfet amplifier. I have the fallowing circuit: Since this circuit was taken ...
38 views

Transconductance of devices

I wanted to ask what are the cases when it's compulosory to know the transconductance (gm) of a device, whether it is BJT, JFET, MOSFET... As far as I know, when you want fast switching with very ...
166 views

Transconductance of a device

I would like to know what does it mean when someone says "that the transconductance of a FET or MOSFET is less compared to that of a bipolar junction transistor (BJT)". I even heard someone saying ...
1k views

Mosfet Voltage Gain in common-source configuration

I have some doubts about this so-called transconductance which can be either calculated for BJT or for FET transistors. As far as I know, since BJTs are current controled devices, its transconductance ...
213 views

Subthreshold Transconductance Amplifier

As part of a broader project, I am designing IC circuit using CMOS to one of the first steps I'm working on is the filtering a series of pulses with of the noise. The actual pulses are around 1 kHz so ...
92 views

Is transconductance concept more important for FETs than in BJTs

In some texts I encounter they mention transconductance when it comes to FETs not BJTs. I have seen myself many texts and skimmed through them, the word transconductance does not appear until FETs. ...
112 views

what is normalized transconductance uesd for?

The transconductance is defined e.g. for BJT by gm = dIc/dVBE with VCE=const (1) where Ic is the collector current and VBE is base-emitter voltage, and from (...
396 views

Why is higher transconductance relates to faster transistor switch?

Here is a quote from this site: ...higher 'transconductance' - a measure of the performance of a transistor - than silicon transistors. The higher the transconductance, the faster the ...
5k views

Transconductance of a MOSFET

I am trying to understand this formula to find the transconductance of a MOSFET transistor, but I am not getting the passage from the second to the third line. What happened there? Thank you
123 views

Voltage to current converter using transconductance amplifiers, OPA860 and OPA861

I want to generate an ac current signal of 100 $\mu$A(peak to peak) with a bias current of 50 $\mu$A upto 100MHz frequency. This will be the input to a $20 k \Omega$ load. I searched for some ...
67 views

Lack of data when performing hand calculations

This question refers to BJTs, FETs, MOSFETs, etc. When I am designing a one or more staged BJT transistor circuit I am often considering differential base-emitter resistance aka "rπ" and finite ...
467 views

Importance of Body Transconductance MOSFET

I am currently studying about small signal models of Common Drain & Common Gate configuration, where the body transconductance has significant effect on voltage gain and output resistance (when ...
692 views

FET Practical DC Analysis Problems

I just finished with theory understanding of FET transistor principles, etc. Right after that I tried to make simple circuit Common-Source with FET and MOSFET the problems occurred one by another. I ...
2k views

MOSFET Basic Biasing Problems

After a lot of theoretical studying of MOSFETs, I decided to try out at least the basics of it in practice. Here is the first circuit I ever made using MOSFET: simulate this circuit – ...
3k views

Change of transconductance for MOSFET

This plot represents drain current versus gate-source voltage (with different ranges of temperature): Often the transconductance of MOSFET is defined as . What is the difference between upper ...
1k views

JFET - transconductance, gain(mu) and internal resistance at the drain

Hello guys, here is such assignment: to determine gm, internal resistance at the drain and maximum gain (mu). 1) If Transconductance gm can be found from the formulas and graph. 2) How to determine ...
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How do I find transconductance from a biased circuit?

I am new to biasing and have trouble finding the transconductance $g_{m1}'$ for this biased differential amplifier below. I know that $V_{BE} = 0.6$ V and $g_{m1}' = \frac{I_c}{V_T}$ but ...
1k views

Transconductance of a nmos transistor

Can anyone explain me how I can find gm from this schematic below (for a nmos transistor)when VGS=6V and VDS=6V?
366 views

Transresistance amplifier and current measuring

I was studying some shunt voltage amplifiers, and I came out with this circuit. R2 is for input voltage offset compensation only, and is the same value as R1. simulate this circuit – Schematic ...
985 views

About BJT, JFET & MOSFET transconductance

For BJT, the term "gm" refers to base-emitter conductance. But when we are talking about FETs and MOSFETs, where is this "gm"? Between gate-source junction for JFET? Drain to source conductance for ...
538 views

JFET transconductance vs. MOSFET transconductance

JFET's n-channel highest transconductance (from datasheets) is marked as In theory, the same value is defined as that applies for n-channel JFET. I haven't found equation which defines MOSFET's ...