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Questions tagged [saturation]

Saturation applies to two things in electronics; core saturation in a transformer or inductor, AND transistor saturation in a BJT or a MOSFET.

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Strange asymmetric saturation with ADA4099

Good afternoon — my first question here, I hope I follow all the rules... So, I am trying to design a series of filters with op-amps that have a shutdown pin, using only 0 ­→ 3.3V supply and an analog ...
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Energy stored in a saturating inductor

We all know that the energy stored in an ideal inductor is \$E=\frac{1}{2}LI^2\$. However, real inductors with a ferromagnetic core don't have constant inductance. Particularly, when a specific field ...
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Inductance after core saturation

Looking at the datasheets of some drum core inductors, at higher currents the inductance drops significantly due to ferrite core saturation. But it seems inductance asymptotically approaches a value ...
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Photodiode Signal Temporal Broadening Below Saturation

I'm a physics PhD student working on a project to use silicon photodiodes for detection of longwave infrared (6-10um) ultrashort pulses. (Specifically doing higher-order autocorrelation) Despite ...
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Why does pinch-off occur in a MOSFET?

Considering an n-channel MOSFET with the source and the substrate at the same potential and the drain at a higher potential, although the potential difference across the oxide layer decreases along ...
Qwertyuiop's user avatar
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3 answers
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Photodiode Circuit Output Saturating to 0V. Is there a way to salvage these boards?

My colleague and I recently designed and ordered a PCB intended to capture red laser light using a SFH2440 photodiode. We used the analog devices photodiode circuit design wizard to design the ...
Jort2750's user avatar
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1 answer
61 views

LNA operating in saturation

What happens to an LNA noise figure when operated in saturation? I understand that there will be gain and linearity issues, but what about its noise figure? What is the mechanism which will lead to ...
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JFET Pinch-off voltage or threshold voltage

the operating condition of JFET in saturation is stated below from this website. Vp stands for pinch-off voltage in the article. But after reading this post shouldn't Vp change to Vthreshold in Vds ...
Jack Huang's user avatar
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5 answers
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TAOE3, Exercise 2.13 -> Verify that a 8°C rise will cause grounded emitter BJT to saturate

I have a question about this circuit from the Art Of Electronics by Paul Horowitz & Winfield Hill, 3rd Edition, Figure 2.44 below. For reference, we just learned about the Ebers-Moll equations and ...
AJ_Smoothie's user avatar
4 votes
6 answers
734 views

Saturation region of BJT

The figure here presents the output characteristics of a common emitter BJT. My question is that why the region mentioned as saturated region is known as the saturation region? As far as I know is ...
Alex's user avatar
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Do FETs need to be biased?

From my knowledge, BJTs need to be biased to control its linearity and gain, usually with resistors on the base and collector. Suppose I want a FET in saturation acting as a high-side switch. Do FETs ...
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Saturation of controlled voltage source

I have simulated a voltage controlled current source based on the article in the link; the LTspice file is also attached. I think my MOSFETs are saturated, so I get almost constant current on the ...
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Saturation mode transistor [closed]

Can somebody explain in a more mathematically way when and how a transistor enters its saturation mode, that's for example the case in a constant current source. I understand the consequences but not ...
olympus_mons's user avatar
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How to design an inductor for the output of a low-pass filter for a 10 kVA sinusoidal UPS

The problem is that I have a 10 kVA sinusoidal UPS to repair and after replacing all the IGBTs and other components, I noticed that the low-pass filter output inductor is getting very hot at around ...
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1 answer
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Confusion in pulse transformer specification

I am having hard time to understand specification of this particular datasheet. https://www.mouser.ca/datasheet/2/54/hctsm8-3217781.pdf I am using HCTSM80101AAL. My first question is about volt-...
igor's user avatar
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4 answers
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Operating regions of BJT

My text book says in saturation mode, the base-emitter and collector-base junctions of BJT are forward biased and in cut-off mode both junctions are reverse biased. But in this graph the saturation ...
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5 answers
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Behavior of BJT collector current in saturation [closed]

Let's assume that we have NPN BJT with absolute maximum rating of collector current = 1A. Let's assume that we have separate power supplies for base-emitter and collector-emitter. The collector-...
Brutal's user avatar
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3 phase 4 wire inverter output common mode choke selection

I designe and develope a stand alone 3 phase four wire inverter that it works with unbalanced output currents. The standard 3 phase 3 wire inverter output are used common mode choke like this (RB6132-...
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4 answers
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Transformer saturation value in volt-seconds

I have a slight confusion regarding the saturation rating of transformers. I often find this value stated in Volt-Seconds, which is a unit for the saturation flux, i.e. the maximum flux that the core ...
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BC547 doesn't give gain for 100 ms, saturation

Why doesn't the BC547 give gain for 100 ms pulse? Need to drive into saturation? Later use 2n2222 or 2n2219 for 5 leds in parallel in saturation mode. Will it go into saturation at 3 volts. Should I ...
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Op-amp not amplifying noise correctly - saturating

I'm trying to produce white noise using an NPN transistor and amplify it using an op-amp. But the signal is being saturated as you see. I'd like to know how to change this setup to make it work ...
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1 answer
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Mosfet Linear Region LTspice simulation

I have a question regarding a mosfet simulation I am trying to perform. Here is the circuit in question. We can see that Vd=1kV , Vs=0V and Vg=10V(it is a pulsed source) Now to my understanding I ...
DRF's user avatar
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2 answers
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MOSFET not saturating when Vds > Vgs - Vth

According to Wikipedia, the drain current (\$I_d\$) should stay relatively constant when \$V_{ds} > V_{gs} - V_{th}\$: (By User:CyrilB - File:IvsV_mosfet.png, CC BY-SA 3.0, https://commons....
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Transistor switching

I am using transistor as a switch, But am having a slight confusion. I am using the diagram below where I am using a 10ohm resistor. As I start switching the transistor instead of going into ...
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540 views

How would the Collector Current be affected during Saturation mode in a NPN Transistor?

From my knowledge, In active mode of operation of a NPN transistor, Base-Emitter Junction is in Forward Bias, and Collector-Base Junction is in Reverse Bias. Width of Base is very low. During ...
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2 votes
2 answers
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Opamp unintended saturation state

I have this circuit which is part of a bigger schematic used for capacitance measurement. This circuit should output 7.5V as the opamp is configured as a repeater and the input voltage is 7.5V (15V ...
Valentin's user avatar
1 vote
2 answers
394 views

How do I measure the output impedance of an inverting op-amp built with the LM741?

I am trying to measure the output impedance of an inverting op-amp. I tried it by connecting a variable resistor to the output. My objective was to use that resistor and output impedance as a voltage ...
Isuru Bhathiya's user avatar
3 votes
2 answers
706 views

What happens when Vdrain is greater than Vsource in PMOS Transistor?

So as I understand, if Vsd = 0 in a pmos transistor, then the current flow should be zero, and the same goes for if Vs<Vd, now my question is, in what state will be the transistor i.e. cut-off, ...
Nemo Holmes's user avatar
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What is the quiescent power dissipated by a TTL totem-pole output stage?

In High-Speed Digital Design by Johnson and Graham, the quiescent power of a TTL totem-pole is given as: $$P_{quies} = \frac{0.4I_{sink} + 1.0I_{source}}{2}$$ I am fairly certain the 1.0 is a mistake ...
John Arg's user avatar
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2 answers
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How to correctly bias an NPN transistor without allowing base voltage to be too high

simulate this circuit – Schematic created using CircuitLab I am trying to correctly bias a BC337 NPN whose collector is connected to a 9V source. I wish to use it as a switch in response to a ...
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3 votes
1 answer
168 views

Questions about current transformer

I am currently trying to understand the influence of the number of windings and load resistor on the current output of a current transformer (CT). My schematic consists of a CT, a load, a divider ...
MakePlatanGreatAgain's user avatar
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3 answers
78 views

How do I select a transistor base's parameters for controlling a solenoid?

I have a small solenoid which is to be powered by a DC power supply. Current is 5A. Resistance is 3.5 ohms. I only want this solenoid to be on for around 20 ms, so I figured a transistor was the best ...
JP12321's user avatar
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0 answers
546 views

Saturation current of Common Mode Choke

I am currently designing a driver for a brushed DC-Motor. The motor is driven by a full bridge (PWM) that switches at about 20kHz. For our application, it is required to increase the inductance of the ...
Mau5's user avatar
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0 answers
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HEMT device not entering breakdown region on Silvaco TCAD during IdVd analysis.What must I do to cause my device to breakdown?

I've been trying to create a HEMT device over the past couple of weeks in Silvaco TCAD. My device works just fine in low voltage operation- that is, IdVg and IdVd curves are as expected. I'm getting a ...
Soumak Nandi's user avatar
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1 answer
851 views

Checking the operating region of a MOSFET in an LTspice DC circuit

I have a relatively complex circuit made of several nMOS and pMOS for which I am performing a .op analysis. This results in a list of the transistors' voltages and ...
none none's user avatar
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3 answers
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BJT: Relation between Ic and Ib in saturation

What is the relation between Ic and Ib in saturation for a BJT? In some places I have seen that in saturation Ic < βIb. Is this true, and if yes, why?
Confused's user avatar
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2 votes
1 answer
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Multi-winding transformers benefits? (DC/DC converter applications)

I've observed that many isolated DC/DC converters use multi-winding transformers and I started wondering why engineers go for this option. So, apart from having multiple isolated outputs or outputs ...
HatimB's user avatar
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1 vote
4 answers
352 views

BJT: How can the potential of B be above that of C during saturation?

I'm learning how BJTs work. As I understand, the B-E junction acts as a diode. This should mean that the potential of B can never be much higher than E besides the usual forward drop of a usual diode (...
mo FEAR's user avatar
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8 votes
2 answers
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I designed and built an op-amp using 4 NPN and 2 PNP BJTs. What are the pros and cons, and how can it be improved?

There have been some questions asked recently about op-amps, and I was curious to see how to make one with just NPN and PNP transistors. I did a simulation in LTspice and it seems to work pretty well, ...
PStechPaul's user avatar
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2 votes
1 answer
137 views

Why do these high-side vs. low-side transistor switch circuits not both operate in a saturated mode?

I need help understanding why these two circuits designed to be the input to a microcontroller logic-level GPIO pin operate completely differently. Green is the voltage at "output" and blue ...
FDecker's user avatar
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4 votes
1 answer
271 views

Does a parallel air gap increase or decrease maximum energy stored in magnetic field of an inductor?

I understand that a serial air gap increases the amount of energy that can be stored in an inductor. The reasoning is as follows: according to Gauss's law for magnetism, divergence of B-field is zero. ...
juhist's user avatar
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NMOS Circuit analysis where the drain and gate are the same

I was trying to solve the following circuit where I have to calculate I_DS and V_DS in the following circuit. So the first thing I noticed, since that the gate and drain are connected, is that this ...
Sydon's user avatar
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4 votes
3 answers
952 views

Is the Rds(on) of a MOSFET typically specified at the boundary of the saturation and triode regions?

Datasheets specify the Rds(on) of a MOSFET at some specific gate-source voltage, e.g. 100mΩ @ Vgs=4V. Up until now, I assumed that the test gate-source voltage was essentially arbitrary and chosen ...
Polynomial's user avatar
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2 votes
1 answer
264 views

Is this a reasonable way to determine if an optocoupler transistor is operating in the saturated region?

I found myself thinking about some 50, old (20+ years) optocouplers that I have (removed from working equipment, purchased somewhere or other, or I don’t remember where they came from), and began to ...
DrG's user avatar
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1 vote
1 answer
226 views

SOA and varying VDS

In a hot-swap application the FET spends some time in the linear region/Saturation region before it moves into the ohmic region. Here is a snippet of the turn on waveform seen for a FET: Yellow is ...
Hasman404's user avatar
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1 vote
1 answer
285 views

How to determine saturation in DC smoothing choke with capacitor, and how to simulate in LTspice?

This question addresses some of the issues with a choke made from a microwave oven transformer for producing smooth DC from a phase-fired SCR controller, as discussed in this question. The choke ...
PStechPaul's user avatar
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0 answers
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Compromising between Inrush and turn on time for MOSFET SOA operation

A hostwap controller as the shown here is used to to precharge and control a high side load: In a hotswap control Q1 will spend some time in the saturation region during start up and turn off to ...
Hasman404's user avatar
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-1 votes
1 answer
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Formula to calculate saturation parameters of a power transformer?

I have recently learnt to build power transformers, my requirement is to make primary core reach right below saturation. I researched on google and found that load current has nothing to do with the ...
Yogie's user avatar
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0 votes
2 answers
255 views

BJT saturation region problem [closed]

I have a graph and a definition like below: Saturation is the state of a BJT in which the collector current has reached a maximum and is independent of the base current. Assume that \$V_{BE}=1V\$, \$...
Becker's user avatar
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2 votes
1 answer
108 views

ADS1113 ADC saturation at 0 Volts while sampling bipolar signal

I'm using a ADS1113 delta-sigma 16-bit ADC to sample a bipolar signal from a force sensor at 50Hz, and I have found a weird phenomenon. When the signal negative or positive, there is no issue, but ...
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