Questions tagged [transconductance]
The transconductance tag has no usage guidance.
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1answer
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 ...
3
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1answer
72 views
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 ?
2
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1answer
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 "...
2
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3answers
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 ...
0
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1answer
73 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 ...
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3answers
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,...
0
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1answer
88 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
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1answer
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 ...
1
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1answer
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 ...
0
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1answer
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 ...
0
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1answer
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 ...
0
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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
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1answer
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 ...
2
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1answer
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. ...
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0answers
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 (...
3
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2answers
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 ...
1
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1answer
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
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0answers
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 ...
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2answers
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 ...
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2answers
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 ...
0
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1answer
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 ...
1
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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 – ...
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3answers
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 ...
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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 ...
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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
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1answer
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 ...
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2answers
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 ...
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0answers
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 ...
1
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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 ...
4
votes
2answers
1k 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 ...
