# Questions tagged [transconductance]

The transconductance of a device relates the current through the output of the device to the voltage across the input of the device.

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### Dot parameters LTspice - Transconductance of MOSFET

Below is a very simple circuit to extract the transconductance value of the MOSFET. As it is known, transconductance is known as Delta (Id) / Delta (Vgate). For the gate voltage, I defined it as .step ...
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### Analyzing $g_m$ vs $V_{in}$ for a common source config

I had this doubt while going through the book "Design of Analog CMOS Integrated Circuits" by B. Razavi, if we are to plot $g_m$ vs $V_{in}$ for the above circuit, then we have $g_m$ =0 ...
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Hello, I am curious about hand calculation about overall Gm by using short circuit transconductance. I got M2 of gm is 1.176mA/V, M2 of gmb is 0.2078mA/V. It should be around 1.14mA/V by using short ...
1 vote
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### MOS transconductance plot using LTspice

I am trying to plot the transconductance of a MOS using LTspice in DC sweep. However, I heard that there is no dy/dx function in LTspice. Therefore, I came up with another way. Keep the drain voltage ...
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### MOSFET transconductance

I am curious what the relationship is between the drain bias current and the transconductance of a MOSFET? For instance, say you set V_DS but you double the drain bias current, how would this affect ...
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### Fully Differential OTA

Based on the figure below, could you explain how a differential ota works ? how can I get the transfert function if I want to set a pole or a zero at the output with a differential resistor and a ...
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### What would happen to the drain current of a D-MOSFET at cutoff voltage when we are going to plot the tranconductance curve?

Here, $$I_{DSS} = 8 \,\textrm{mA}$$ $$V_P = -6 \,\textrm{V}$$ Equation for the drain current, $$I_D = I_{DSS} \left(1 - \frac{V_{GS}}{V_P}\right)^2$$ So, the cut-off voltage is where the Drain ...
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### Finding transconductace Gm=Isc/Vin for a common source MOS amplfier with source degeneration

I am looking to find short circuit current over input voltage to find transconductance Gm for a common source amplifier with source degeneration. To do this, I first shorted the output terminal and ...
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### Cannot Find MOSFET Transconductance - Incredibly Confused

I am tasked to find the gain of this small signal circuit drawn in my work. I have absolutely, NO idea how the professor came up with his answer. I would e-mail him, but he doesn't respond on weekends....
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### Transconductance photodiode?

I'm having trouble finding a theoretical explanation about the transconductance photodiode behavior, the materials I find on the internet they talk about the connections, but not the behavior, in case ...
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### What is dynamic range in MOS transistor?

In Analog CMOS integrated circuit book, page 696, edition 2, it is stated that: In order to restore the dynamic range, the transconductance of the transistors must be increased by a factor of square ...
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### Converting 1 - 5V signal to 4 - 20mA signal

reference: https://www.analog.com/media/en/technical-documentation/technical-articles/D61_EN-Convert.pdf I am trying to convert a 1-5V signal to a 4-20mA signal using this circuit but it was not ...
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### Interview Question

This Circuit was given. While I possess knowledge of each component within this circuit, including an understanding of feedback and gain margin, as well as familiarity with transconductance ...
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### How to derive effective transconductance versus oscillation amplitude in a oscillator?

In the page below in the lecture note shows a plot of effective transconductance versus oscillation amplitude. How is it derived? Or is there any source to derive effective transconductance versus ...
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### Bidirectional voltage-to-current converter

How to make the following voltage-to-current converter bidirectional, so that bidirectional current can be driven through the load?
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### Push-Pull voltage-to-current converter

How to make the following voltage-to-current converter bidirectional, so that it maintains the requested current through the load, even when that load stores energy and attempts to oppose the ...
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### Calculation of transconductance in a MOSFET

I am teaching electronics. I have come across this formula for drain current in the syllabus that I am teaching. However, I have never seen it before. My question is where is this number -3 from ...
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### Interpreting the value of transconductance shown in a MOSFET datasheet. Why was that particular value chosen to be shown?

Context: I'm a beginner in electronics, self studying MOSFETS. I'm trying to understand why the manufacturer of this MOSFET decided to provide a single particular transconductance value in the ...
1 vote
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### how to calculate rx, ro given gx and go from XSPICE

I have a set of XSPICE data extracted from multisim as can be seen in the attached image. How do I calculate the ro and rx (base spreading resistance) given the parameters go and gx. Thanks
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### Output resistance and transconductance in the calculation of NMOS common source voltage gain

For a NMOS, the transconductance gm is defined as id/vgs at a fixed VDS. However when we calculate the small signal gain of a common source amplifier, we use vds = -id x RD and then vds = -gm x vgs x ...
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### Does transconductance of a NMOS in saturation vary if I double both 'W' and 'L'?

Gm for a mosfet in saturation is 2Id/Vov. Vov is constant and we expected the Id to be a constant too for both cases since Id(sat)=0.5*UnCox (W/L)(Vov^2), W/L is unchanged and there for Id should be a ...
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### What makes transconductance negative?

Quote... "transconductance is -1 amps/volt" Refer to this link for the source of my question... This reference lacks the negation of A/V while this reference includes it? I'm confused...to ...
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### Transconductance of MOSFET with channel-length modulation

As far as I understood, I think it could be derived as below. $$g_m = \frac{\sigma I_D}{\sigma V_{GS}} = \mu_n C_{ox} \frac{W}{L}(V_{GS}-V_{TH})(1+\lambda V_{DS})$$  = \sqrt{2\mu_n C_{ox}\frac{W}{...
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### Gmo2 from vout about differential amplificator

I'd like to know if this demostration is correct to calculate Gmo2 from vout about differential amplificator from this diagram : 1 : Gmo transconductance about Common Base configuration 2 : Gmo1 ...
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### How to experimentally calculate transconductance of an OTA?

How can I experimentally calculate the transconductance of an Operational Transconductance Amplifier given that I know the value of bias current ?
1 vote
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### Mathematical Model for SiC MOSFET C2M0080120D, transconductance and capacities [closed]

I am currently trying to use the model described in the paper "An Improved Analytical Model for Predicting the Switching Performance of SiC MOSFETs" in MathLab to simulate/imitate it. The paper can be ...
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### 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 ?
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### 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 "...
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### 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 ...
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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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### 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 ...
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