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Questions tagged [saturation]

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3answers
72 views

Transistor Analysis

Here is a problem I saw as an example of transistor analysis: (hFE is 50) simulate this circuit – Schematic created using CircuitLab The process is simple, the guy assumed that the transistor ...
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0answers
39 views

op amp saturation

I have this circuit which is acting with negative resistance. However when increasing the voltage well above saturation it produces a weird distortion on the output as seen below. can anyone explain.
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1answer
100 views

Inverting op amp design saturates at a fraction of power supply

I have built a simple inverting op amp. I am applying a 1 Vpp sinusoid at 10 Hz to a design with ~4.7x gain. The resistors I am using are 47kOhm and 10 kOhm. The op amp chip is the LT1222, and I am ...
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2answers
32 views

On interpreting this set of curves (Transistor in Saturation mode and decrease of \$h_{FE}\$)

The following figure was excerpted from Horowitz's The Art of Electronics, Appendix G: Transistor Saturation (page 1089 for the 2nd edition), It represents the current gain \$\beta\$ of an npn ...
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1answer
63 views

Rectified current transformer output is asymmetric

I'm using a current transformer (CS4200V-01L) to measure the current in a half-bridge. I'm facing an issue where the signal out of the current transformer is asymmetric, almost as if the current ...
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1answer
48 views

How can U_CE be smaller than U_BE in this circuit?

Recently I was wondering why UCE can be smaller than UBE. I've drawn a small diagram with the typical values of the BC547 NPN transistor. This amazes me all the more as UBE shares its PN-regions with ...
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4answers
222 views

What are these transistors doing and how are they working in this VU Meter?

I was thinking of making KITT's voice box from Knight Rider, which is essentially a VU meter. I did some researching and found an appropriate IC, LM3916, http://www.mouser.com/ds/2/405/lm3915-443929....
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1answer
114 views

How to Calculate Saturation Current of a Transformer?

Is this Method applicable to calculate? My confusion is mainly regarding with Load current. My knowledge is, that load current is nothing to do with saturation of transformer.
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0answers
82 views

Can an inductor lose its characteristics permanently after short saturation?

I was testing a SMPS (boost) where I had an overcurrent due to overload for a few seconds. The inductor saturation current is 2A. Although I could not measure the current, I am quite sure that the ...
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0answers
30 views

Understanding PMOS's and NMOS's

The problem says solve assuming VI = 0, +2.5V, and -2.5V. I know that if VI = -2.5V the MOSFET's are in cutoff and that VDS = 0. and IDP and IDN will = 0, but would V0 also = 0? If VI = 0 the ...
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1answer
57 views

Instrumentation Amplifier Saturation to Rails

I am working with a TI INA821 Instrumentation Amplifier to try to amplifier a 0-5mV (delta) analog signal off a strain gauge. To reiterate, every DC analog value between the delta of 5mV represents a ...
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2answers
39 views

Magnitude of \$I_{CBO}\$ in a typical transistor

I read in a book that \$I_{CBO}\$ doubles for every 10 degree rise in temperature and hence contributes to thermal runaway. However I am confused since essentially it is the reverse saturation current ...
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0answers
43 views

Usuing P_channel mosfet to make o normally closed switch

Hi, I am trying to implement a normally closed switch. In the shown circuit: Vcc = 16..60V (Vcc>>Vz) The characteristics of the P-mos are: Vth = -1V Rdson = 0,055ohm The circuit works correctly: in ...
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3answers
61 views

Saturation current on chip inductors

Inductors are really not my strong point, and I have been getting a bit confused on the rated current vs saturation current. I know the rated current is how much current the inductor can handle ...
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1answer
66 views

Magnetic material demagnetization through Curie temperature

It is known that some materials lose their permanent magnetic properties when they are heated above certain temperature known as Curie temperature or Curie point. As those materials are cooled down to ...
2
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1answer
103 views

Do BJT (Darlington) transistors have a minimum collector current?

I am using a TIP122 Darlington transistor. From the graph provided in the datasheet, I can see that the saturation voltage decreases as the collector current decreases. Since the load I am driving ...
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1answer
98 views

Why isn't the Saturation Current of a Photodiode the same as its Short Circuit Current?

The formula I see everywhere is: $$ I_{sat} = \frac{V_{bias}}{R_L} $$ But this seems incomplete for the following reason: The larger the resistance is the smaller the Saturation Current, it stands ...
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1answer
60 views

What part of Ebers-Moll equation shows the decrease of the collector current in saturation region

By looking at the Ebers-Moll equation for a BJT transistor: Is this formula explicitly showing why Ic starting to decrease towards zero in saturation region. Which part of the equation shows that?
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2answers
220 views

Where would Iceo flow through and would it cause thermal runaway?

I was reading this page about thermal run away. And it mentions: Due to increase in the temperature of collector junction, Ico will increase, Vbe will decrease. But for Ico to increase Ic and ...
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1answer
78 views

MOSFET goes into saturation mode much later

I am using IRLML6346 NMOS in LTSpice. Its threshold voltage is Vt = 0.95V. I plotted the graph of Vds(voltage between drain and source) vs Ids(Current from drain to source) for different values of Vgs(...
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1answer
54 views

BJT saturation question

For the following question, how do we find \$I_B\$ and \$I_C\$? Would it be $$I_C = \frac{V_{in}-V_{BE}}{80k}$$ and $$I_B = \frac{12-0.12}{5k}$$
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132 views

NMOS/PMOS Saturation

If I recall correctly, saturation occurs if \$V_{GS}>V_{TH}\$ and \$V_{DS}>V_{Dsat}\$ for NMOS. But is there an upper limit for the voltage? Like, when does a transistor not saturate after ...
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1answer
132 views

Double BJT circuit with one BJT off and one in saturation

In the circuit below, due to the base voltage, the circuit becomes a common-emitter setup. However, assuming a reasonable value for the base current the BJT should be in saturation. However the value ...
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1answer
74 views

How can a magnetic circuit with an airgap have a higher e.m.f in the secondary coil than the same circuit without the air gap?

I have a magnetic circuit with the same configuration as in the image, the primary coil has 203 turns and the secondary has 406 turns, how do I get a higher eletromotive force when there is an air gap ...
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2answers
250 views

Self-made Schottky transistor doesn't behave as I'd expect

For a project of mine I need to generate UART-like signals with higher voltage (up to 18V) and a baudrate of 115200 bps and later possibly 250000 bps. I tried a basic BJT level shifter which worked as ...
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2answers
1k views

BJT: Equation of Vce for Saturation Region

In Sedra and Smith: Microelectronics Circuits (6E), it is mentioned, on page 185: Recalling that the CBJ is much larger than the EBJ, the forward-voltage drop \$v_{BC}\$ will be smaller than \$v_{...
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1answer
186 views

Differential amplifier circuit, problem with saturation

I have a homework problem regarding differential amplifier. We have a differential amplifier with symmetric supply (i.e. \$V_{CC}=-V_{EE}\$). Emitters are connected to a perfect current source \...
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2answers
165 views

OPAMP saturating when output is negative, simulation is OK

The schematics: It should convert 0-3.3V input from the DAC to -4.1 + 4.1V (roughly) The positive part works great, the negative output voltage saturates at -2.95V. Is it ok? The simulation looks ...
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1answer
147 views

Saturation Cascade MOSFETS (Need Help from EE Experts)

this is a very straightforward question. I'm running a Harmonic simulation on ADS where I need to design a cascode amplifier of two NMOS and one PMOS, that have a gain higher than Av > -100. The ...
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1answer
464 views

Problem with output swing in LM358

simulate this circuit – Schematic created using CircuitLab I am working on a battery charger with indicator. I am using a LM358 to compare the voltage of my battery with a reference voltage of ...
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1answer
212 views

Do we have a voltage drop across this ideal current source?

Additional info includes Vss=0V, Vdd=3V. Also assume saturation (since we have Vd=Vg) and λn=0. We also know the reference current but not the Resistor. I know Vgs and thus Vds but I am looking to ...
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2answers
447 views

Why collector current is small in value in saturation mode?

Why is the collector current smaller in value when a transistor is in saturation mode of operation? My guess is that although both the junctions are forward biased, the (forward) currents are '...
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1answer
153 views

JFET saturation current

Is it possible to analytically calculate Idss for JFET? I tried by setting voltage gate-source to zero, and then finding the drain current, but it doesn't seem to match with the given value?
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1answer
88 views

Why this operational amplifier is saturated?

my problem is that in this circuit: Where \$\pm V_{cc} =\pm 15V, R1=1k\Omega, R2= 10k\Omega\$, if I introduce a signal like: \$ v_i(t) = 2 \cos{(2\pi 1000 t)}\$, the output voltaje is this: Where ...
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1answer
349 views

Simulating Chua's circuit in LTspice with a saturating transformer-based nonlinear resistor

Chua's circuit is one of the simplest circuits known to exhibit chaotic behavior. It consists of resistors, capacitors, an inductor, and an active nonlinear resistor. One implementation of this ...
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1answer
164 views

Photodiode amplification works with LM258N but doesn't with LF356N

The circuit is as follows I'm powering the op-amp from a 9V battery. It gives me constant 3.6V at the output and it doesn't change with changing the illumination of the diode. I tried replacing the ...
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2answers
2k views

What is the difference between “Collector-Emitter” and “Base-Emitter” Saturation Voltage?

As you can see on the datasheet below for the 2n2222a NPN transistor, the "Collector-Emitter Saturation Voltage" and "Base-Emitter Saturation Voltage" are defined respectively as 0.3 to 1.0 and 1.2 to ...
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1answer
241 views

Cannot find “reverse saturation current” of base-emitter junction in the data-sheet

Regarding the reverse saturation current \$I_{ES}\$ aka \$ I_{EO}\$ of an NPN transistor, according to Ebers–Moll Model: \$I_E = I_{ES} (e^{V_{BE}/V_T} -1) -\alpha_RI_{CS}(e^{V_{BC}/V_T}-1)\$ ...
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2answers
227 views

Saturating magnetic field in an inductor without heating

I am building an RL series circuit with a toroidal inductor that I am winding on my own. The toroid is made of steel (low carbon, I believe, but not 100% sure) and has about 280 turns of 22 gauge wire....
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6answers
2k views

Why do we want gap in the core material while designing inductor?

In some cases it is necessary that core of inductor should have a gap, unlike with transformer core. I understand the reason with the voltage transformer core; there is nothing to worry about core ...
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4answers
1k views

Negative voltage for Vce - BJT NPN

I was wondering what happens when VCE voltage becomes negative? suppose I am forwarding both junctions (no resistors). I know that saturation happens when VCE is between 0.1V- 0.3V but what happens ...
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1answer
1k views

Vce saturation voltage confusion

I finally finished my first transistor circuit and looks as follows: For the LED to light up properly, I assumed a forward current of 70mA and a voltage drop of 1.3V. The datasheet of the PN2222A ...
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3answers
950 views

How to determine the saturation level when an opamp schmitt trigger starts worknig?

The Opamp inverting schmitt trigger is constructed as shown. The output signal is So I ask why is the output at the start of operation saturated to positive? Also, if the input voltage is moved ...
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2answers
249 views

Powering an LED with transistor in saturation mode

I currently try to design my first transistor circuit to switch an LED on and off. So I came up with this circuit diagram: I have to use the following components: PN2222A NPN BJT IR LED TSAL 6200 ...
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2answers
404 views

Current increase in induction motor

I have an induction motor which is fed by a three phase inverter. I am trying to use vector control with d-axis aligned with the rotor flux vector. I have a load which increases its torque as the ...
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4answers
2k views

NPN Circuit simulation doesn't agree with book

I'm trying to understand an exercise reported in Microelectronic Circuit Design by R. C. Jaeger & T. N. Blalock (4th ed, p.237). $$\beta_F = 50, \beta_R = 1$$. I don't agree with the discussion ...
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1answer
104 views

Opamp circuit problem

BJT Circuit Problem I have already posted a similar problem in the link above. I am facing the same issue in this circuit. What will be the state of the 2 BJT's Cutoff, Saturated or Active ? Please ...
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2answers
536 views

BJT Circuit Problem [closed]

I am facing problem in solving such mixed circuits with bjt, diode, opamp and Zener diode. In the above problem 1.zener can have 3 states (ON, OFF, Reverse ON) 2.diode can have 2 (ON, OFF) 3.BJT ...
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2answers
889 views

How to conclude region of operation for a series combination of MOSFET

I understand that M1 is on and for M2 to be on the intermediate voltage(drain on M1 and source of M2) should be less than 1.5V. Also if M2 is ON then M2 is in saturation since Vds>(Vgs-Vt) for M2. Now ...
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1answer
422 views

Inductor Inrush Current Rating

I am experimenting with the simple circuit shown below and was wondering how to ensure that the inductor used would handle the inrush current. My reasoned solution is the following: I solved for ...