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.
264
questions
1
vote
1
answer
49
views
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 ...
- 438
1
vote
2
answers
52
views
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....
- 217
1
vote
3
answers
332
views
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 ...
user340506
0
votes
3
answers
67
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 ...
- 15
2
votes
2
answers
46
views
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 ...
- 21
1
vote
2
answers
106
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 ...
3
votes
2
answers
556
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, ...
- 33
0
votes
0
answers
46
views
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 ...
- 113
4
votes
2
answers
828
views
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 ...
- 95
3
votes
1
answer
113
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 ...
0
votes
3
answers
67
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 ...
- 1
0
votes
0
answers
238
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 ...
- 140
1
vote
0
answers
57
views
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 ...
- 21
0
votes
0
answers
33
views
What's the relation between SWG, input & output VA, cross sectional area, number of turns of an isolation transformer?
I made 3-4 transformers before and learnt a lot about transformers, I didn't have a formula so I was following heuristic approach to resort to the right SWG and right number of turns, however this ...
- 73
0
votes
1
answer
253
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 ...
- 135
0
votes
3
answers
464
views
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?
- 1,595
2
votes
1
answer
129
views
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 ...
- 826
1
vote
4
answers
160
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 (...
- 264
8
votes
2
answers
1k
views
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, ...
- 7,325
2
votes
1
answer
81
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 ...
- 37
4
votes
1
answer
216
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. ...
- 1,563
0
votes
0
answers
50
views
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 ...
- 95
4
votes
3
answers
627
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 ...
- 10.6k
2
votes
1
answer
153
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 ...
- 655
1
vote
1
answer
159
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 ...
- 727
1
vote
1
answer
180
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 ...
- 7,325
0
votes
0
answers
60
views
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 ...
- 727
-1
votes
1
answer
258
views
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 ...
- 129
0
votes
2
answers
159
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\$, \$...
- 43
2
votes
1
answer
77
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 ...
- 23
2
votes
1
answer
181
views
What do I add across the opamp to get a full sine wave?
I'm struggling to figure out a solution to avoid saturation, I believe the solution will require some component to be attached across the opamp to produce the same voltage out as voltage in (voltage ...
- 23
0
votes
1
answer
76
views
Finding DC saturation behavior of clamp ferrites
While some chip ferrite datasheets specify maximum current and DC saturation behavior, it seems like many clamp ferrites omit both maximum current specification (which arguably is less critical) but ...
1
vote
1
answer
236
views
Cascode: Which device goes into triode region first?
In the above cascode network, which device goes into triode region first, if the supply gradually decreases?
Framing the question other way round, if the supply gradually increases from 0V, which ...
- 131
0
votes
1
answer
119
views
LF411 behavior at -15V
I'm doing the following exercise from the Hayes' "Learning the Art of Electronics"
The circuit behaves as following:
When the pot's output is positive, the opamp's output is saturated at ...
- 69
1
vote
2
answers
419
views
Will the current needed for core saturation (transformer) increase with applied voltage?
I was going through one of the research papers based on self-excited push-pull converters.
The line below is taken from the paper:
the current needed for core saturation rapidly increases with ...
- 11
1
vote
2
answers
183
views
What is the fool-proof method to confirm whether the op-amp has -ve feedback?
As the theory goes, following are the 2 cases of op-amp operation:
If there is a valid -ve feedback, inverting terminal volt = non inverting terminal voltage
If there is no -ve feedback, o/p acts ...
- 2,621
1
vote
1
answer
281
views
MOSFET PWM issue
I want to dim an LED and have connected a P-channel MOSFET to switch the high side. I added a N-channel MOSFET as a driver. The schematic is attached below.
I'm applying a PWM sine signal from an ...
- 57
3
votes
1
answer
175
views
LTspice - Staircase saturation transformer
I am trying to simulate on a full bridge converter a staircase saturation transformer. I was thinking by adding a very little resistor on one leg of the full brigdge converter, it will in any case ...
- 2,740
-1
votes
1
answer
532
views
Alternator's saturation in load and no-load conditions
When a ferromagnetic material is exposed to a magnetic field in which it moves, some voltage is induced in the material. If you increase the magnetic field, the voltage is increased up to a point, and ...
- 3
2
votes
1
answer
374
views
How does this transistor behave as the base voltage is increased?
Consider this transistor. How do the voltages Vb, Vc and Ve vary as we increase ...
- 139
1
vote
1
answer
482
views
Is there a formula to calculate the saturation current of an inductor or is it only obtained experimentally?
I want to make an inductor for my buck converter since I cannot obtain the recommended inductors for the LM2596.
How do I calculate the saturation current for this inductor if I use a ferrite core?
...
- 633
1
vote
1
answer
250
views
How do I stop buck converter voltage from dropping whenever current increases?
I built this buck converter circuit using the LM2596T-5 (5 V OUTPUT, 12 V INPUT) using the exact components mentioned in the datasheet's first page (schematic below), except for the diode.
I used the ...
- 633
0
votes
1
answer
1k
views
MOSFET in saturation mode
A MOSFET in saturation mode behaves like a constant current source but a current source has infinite output resistance. To make it work like an active load instead of a passive load like a resistor we ...
1
vote
3
answers
574
views
Designing an automotive alternator's voltage regulator - how to avoid magnetic saturation in the rotor?
NB: See final edit. The question is based on a false premise
Friends are making a test-bench for automotive ("Lundell") type alternators.
They were supplied with an example alternator plus a ...
- 5,331
1
vote
5
answers
4k
views
Transistor collector emitter saturation voltage
I am trying to choose a transistor to use in a current mirror to prevent thermal runaway of parallel LEDs (yes I have to connect them in parallel. I know connecting in series or using separate ...
- 382
0
votes
1
answer
167
views
BJT differential pair on breadboard enters saturation
I've built the following circuit on a breadboard (for the purpose of experimentation) and measured the voltages:
IN+ and IN- ...
- 1
1
vote
5
answers
506
views
Saturation for emitter follower
How can a transistor connected in emitter follower configuration be driven into saturation?
I know that for saturation, the base voltage should be greater than the emitter voltage, but also than ...
- 37
0
votes
1
answer
381
views
In the PNP transistor, base current is the sum of emitter and collector current. How is this possible?
The PNP transistor at the right side doesn't follow any characteristics of the 4 modes of operation of BJT. How is this possible? PSPICE simulation has shown quite similar results. Here, beta=100.
- 107
2
votes
1
answer
239
views
Boost converter drive inductor into saturation
The boost converter I'm trying to put together might seem a little bit odd, as it's made out of parts that belong in a museum, but I've quite a lot of them so I thought to use them for something. I ...
- 31
0
votes
0
answers
60
views
What is "level of saturation" for transistors?
This is a term I've never heard of, and it's presented on a work analysis of a ttl nor circuit. It basically says that the transistor that links the output with the ground should have a higher "...
- 103