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Questions tagged [transconductance]

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2
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1answer
30 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 "...
2
votes
3answers
106 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 ...
0
votes
1answer
59 views

Advantages/Disadvantages of high/low transconductance efficiency (gm/Id) of NMOS/PMOS

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 ...
2
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3answers
623 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,...
0
votes
1answer
81 views

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 ...
0
votes
1answer
68 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 ...
1
vote
1answer
601 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 ...
0
votes
1answer
36 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 ...
0
votes
1answer
134 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 ...
0
votes
1answer
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 ...
4
votes
1answer
189 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 ...
2
votes
1answer
88 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. ...
1
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0answers
95 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 (...
3
votes
2answers
327 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 ...
1
vote
1answer
4k 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
1
vote
0answers
110 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 ...
1
vote
2answers
66 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 ...
0
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2answers
439 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 ...
0
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1answer
664 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 ...
1
vote
4answers
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 – ...
0
votes
3answers
2k 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 ...
0
votes
2answers
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 ...
0
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0answers
72 views

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 ...
0
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1answer
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?
0
votes
1answer
359 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 ...
0
votes
2answers
903 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 ...
1
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0answers
514 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 ...
2
votes
2answers
1k views

MOSFET finite output resistance in saturation mode

Since MOSFET has finite output resistance in saturation/active mode, the slope of unsignificanlty rising drain current is defined by Ua and slope parameter as lambda: This parameter (as I know) is ...
5
votes
2answers
985 views

Is the OPA860 a diamond transistor?

I was looking at using the OPA860 for a voltage controlled load. Reading in the OPA860 datasheet it says: The OPA860 combines a high-performance buffer with a transconductance section. This ...