# Questions tagged [saturation]

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### Current gain characteristics versus Collector Emitter voltage. Where is the transistor saturated? Can a transistor be saturated with a VCE of -10V?

I'm fairly new to transistor usage and determining stages of operation for a BJT. However, from what I've learned, in order for a BJT to be saturated, both junctions need to be forward biased, and ...
39 views

### Is possible to get Q2 saturated with the VI voltage?

I´m having trouble with this circuit. Is it possible to get Q2 --> saturation using the VI voltage? When VI = 0; the VCE2 = 14.457 V. By calculations I know that Q1 and Q2 cannot be on saturation at ...
612 views

### Why are the transistors in logic circuits used in saturation region for ON state?

This is a beginner question. I know how the logic gates with BJTs work basically to provide ON and OFF switching action. OFF state occurs when the transistor is blocked in cut-off region, and ON state ...
263 views

### DC Shunt Generation Ascending/Descending Terminal voltage Saturation Curve help?

In a DC Shunt Generator we increased Field Current from 0 to 2.0 and calculated the Terminal Voltage, we then decreased field current from 2.0 to 0 and collected our field current again. When plotting ...
543 views

### Avoiding opamp saturation - working with apd

i have avalanche photo diode with which i am trying to digitalize the current from TIA through a comparator, the diode biased using a HVDCDC the source is being a 20ns laser with a PRF of 3Khz the ...
278 views

### Setting optimum base current for saturation and power dissipation of a BJT

Regarding the following circuit example, I want to find the optimum current for saturation of Q1. By saturation I mean the safe one. For simplicity I didn't bias the transistor and I'm assuming beta ...
167 views

### Some questions about BJT in saturation region

In below circuit I sweep Vb from zero to 5V Vcc. And I obtain the following plots for the currents: I have a bit problem with understanding two things in saturation region: 1-) Why/how does the Ic ...
3k views

### A confusion about the formula for transistor Vbe Ic characterisitcs

Below is NPN BJT transistor Vbe Ic characteristics and the formula: Many texts approximate this equation as: Ic = Is*e^(Vbe/Ut) and following this they say when Vbe=0, Ic becomes equal to Is. ...
174 views

### Does a saturated inductor radiate more?

Background: I am using a shielded inductor in a switching power supply, and am investigating an EMI issue. My hypothesis is that since the inductor is saturated, the magnetic field is no longer ...
1k views

### Is inductor saturation current frequency dependent?

The wiki article explaining inductor core saturation talks about magnetic domains lining up with the external magnetic field to concentrate the magnetic flux. This sounds similar to electric ...
683 views

### How to measure the inverse saturation current of a diode?

I'm trying to measure the inverse saturation current of a diode, for using it in the schockley equation. I would like to know what is the best circuit for doing this. I already tried the following ...
236 views

### Questions regarding BJT saturation for a circuit

I have the following circuit which converts weak sine signal to pulses: I have tried it on breadboard and it seems it works fine. In my application freq. is between 1Hz to 30Hz or max 100Hz. And the ...
519 views

### Why does the reverse saturation current not vary with the reverse voltage?

I can understand that in the depletion region of a diode more covalent bonds are broken(more electrons goes to conduction band) with more temperature hence we say that the reverse saturation current ...
3k views

### Resistance of a MOSFET in saturation mode

I have been studying MOSFETs and have a question regarding saturation mode. To my understanding, the drain current is constant in saturation mode. Does this mean that the drain-source resistance ...
1k views

### Why Does Op-Amp Output Voltage Always Saturate (in a Non-Inverting Amplifier Circuit)?

I am trying to amplify the voltage measured across a shunt resistor (Rs). I am using a non-inverting amplifier circuit (as shown in the figure). The expected voltage across the shunt is in the 0-50mV ...
311 views

### How a switching PSU inductor overcomes the problem of saturation current?

If you open a switching step down converter like the one used in your desktop computer, you will only find that a relatively small torroidal transformer ultimately provide the power to the user. Sure,...
221 views

### What causes a transistor to enter into the saturation mode?

I'm looking into the construction of logic gates, and am wondering what conditions are need across emitter-base-collector in terms of both voltage and current to enter the saturation mode. For ...
686 views

### Current waveform distortion on transformer with a load resistor on secondary winding

Why does the current from a transformer with a load resistor quickly rise and fall (yellow wave-form)? (Transformer without a load resistor (white, primary)).
2k views

### Active region in BJT in a Common emitter configuration

In BJT for working in active region for a common emitter configuration emitter and base should be in forward bias and base and collector should be in reverse bias. But in case of voltage we say that ...
566 views

### Collector current decreases with the increase of base current in saturation mode of bjt

I'm new to BJT and i'm trying to understand the characteristics of bjt in different modes of it. In my book they explained that in saturation mode of bjt the collector current decreases even if i ...
166 views

### Why is one transistor in active and the other in triode?

Vtn = 0.4 V, W = 1um, L1=0.25um, L2=0.5um. For a question I got the circuit above, and the solution said that M1 is in triode and M2 is active. Also, V1 is unknown so I can't figure out how they ...
301 views

### Negative value for saturation mode voltage of MOSFET

I want confirmation of whether a MOSFET is in saturation or not. I have calculated the condition using the formula $V_{GS}-V_{tn}$, and my answer is a negative value. Does it matter if the value is ...
360 views

### Collector voltage in saturation

I saw the following question online I knew that while Vbe was less than 0.6v, there would be no current and the collector voltage would be Vcc. At 0.6V, I knew that the transistor would turn on, and ...
486 views

### Microphone saturation avoiding desired signal from being detected

I'm trying to detect a known signal under heavy interference. I'm working with 2 smartphones and an interfering speaker. I'm sending a signal from one smartphone speaker to the other smartphone ...
238 views

### Opamp output saturates at 1.7V even though rail voltage is 5V

simulate this circuit – Schematic created using CircuitLab I am working on following circuit on a 4 layer PCB. The sensor gives output from 0.5V to 4.5V and has frequency response of 19 Hz ...
2k views

### Reverse saturation currents of a LED?

What are the typical values of reverse saturation current of a LED? In particular is it possible to have a reverse saturation current of $10^{-17} A-10^{-18} A$ for a (red) LED? For a silicon diode ...
357 views

### NPN Switch when ON operating in Forward Active or Saturation Region?

When an NPN transistor is used as a switch as shown below, is it operating in the Forward Active Region or the Saturation region when it is turned ON? I believe its working in the Forward Active ...
925 views

### Saturation current in Ebers-Moll equations for BJT: what is it and how to measure it?

In Ebers-Moll Equations for common emitter BJT the inverse saturation current $I_s$ appears as a parameter. What is the saturation current $I_s$ exactly and how should I measure in a common ...
618 views

### PNP with zener diodes circuit

simulate this circuit – Schematic created using CircuitLab I am really struggling to understand how this circuit works theoretically. What will be the currents through the resistors? My ...
247 views

### Control voltage required to turn on the LED through an NPN

simulate this circuit – Schematic created using CircuitLab For this circuit, I am trying to figure out the value of $V_1$ DC which will turn on the LED, D1. Since the forward voltage drop of ...
100 views

### Channel shape of NMOS in saturation

According to the Sedra/Smith Microelectronic Circuits textbook, 6/7 eds., increasing $v_{DS}$ beyond $v_{OV}$ has no effect on the channel shape and charge. Why is that? It seems as if (...
302 views

### A switching boost converter biasing a tube preamp - saturation issue

I am designing a 9V-battery powered tube preamp (for electric guitar), based on a Russian rod tube (1j24b). The latter is a pentode, and works with about 45V on its screen grid and at least 30V on its ...
83 views

### BJT Differential Amplifier deliberately saturated?

Happy New Year! I've recently completed a metal detector project (see my recent questions) and I've been going back over some of the parts I didn't fully understand first time around. This question ...
78 views

### Horowitz lab 4.4

I have a problem doing lab 4.4 from Horowitz's student manual for the Art of Electronics. Here's the circuit and here's what I get from LTspice simulation, which corresponds to hardware circuit ...
3k views

### How to solve BJT amplifier clipping a signal?

I'm trying to make an audio amplifier for an 8 ohm speaker. I'm new in electronics area and having a problem with it. I already had other issues before arriving where I am, like the need of a high ...
7k views

### A question about Vce of an NPN BJT in saturation region

Below is an NPN transistor symbol and the voltages at its terminals are Vb, Vc and Ve with respect to the ground: I read that: during the saturation the Vce = (Vc-Ve) settles to around 0.2V and the ...
109 views

### output voltage of an operational amplifier

A student designs an electronic sensor to monitor whether the temperature in a refrigerator is above or below a particular value. The circuit is shown below. Question: An operational amplifier (op-...
1k views

### Why Op-Amp Saturation voltage drop with increasing frequency?

i was Implementation of square and triangular wave generator using op-amps LF353. I observed that when I choose different values of Resistor and Capacitor for different frequencies, with increasing ...
49 views

### Calculating minimum resistance such that Ic is less than or equal to the maximum Ic in BJT

This is what I have been given for the question. I'm confused on how to answer this question. I thought this was calculated just by using ohm's law where R = 5V(supply V) / .3A(max Ic) = 18. However ...
3k views

### Output Drift of an operational Integrator

R = 1k and C = 0.1 uF In practice, the output of and operational integrator will (drift) until it saturates at a value close to one of the supply voltages, even when the input voltage (Vin = 0). Why ...
711 views

### Correlation between saturation of high current (power) transformer core and load

In an experiment I need high ($>600A_{max}$ or $1200A_{pp}$) AC currents in a range from 400Hz to 4kHz. The load is simply a short circuit. For this purpose i use a class D audio amplifier and ...
808 views

### Transistor used as switch not working when connecting a water solenoid valve

As a summer project I am trying to create an automatic irrigation system. To do so, I created a circuit with a single transistor which will move from saturation to off and thus behave as a switch. ...
515 views

### Common base circuit with zero supply voltage

Consider a bipolar junction transistor (either PNP or NPN). Which output would produce this circuit for various input ($= V_{\mathrm{BE}}$) voltages? It is common base, but without a voltage supply ...
2k views

### Terminology for BJT “regions of operation”

How regions (modes) of operation are defined and correctly named? The most controversial thing is the so named “saturated region/mode”. It is defined differently, sometimes radically different, in ...
2k views

### How does a photodiode behave in saturation?

In my design, a photo diode is connected in reverse bias with 12V. The LDO (low-dropout) voltage regulator which is used for biasing can deliver a maximum current of 500mA My configuration: simulate ...
10k views

### Why does the opamp output voltage saturate?

simulate this circuit – Schematic created using CircuitLab Vout = Vin (1 + R2/R1) According to this positive feedback topology - made an error here, it's Vout = Vin(-R2/R1) (edit) Now I ...
229 views

### How does the source voltage change with and without channel modulation?

The description here seems big, but it's only a two minute read. I'm stranded, desperately need help. The variable resistance R in the figure is set to 10K ohms. The first question was to find the ...
3k views

### What happens after opamp saturates

here below is a TIA stage intended to do I-V conversion, as the maximum supply voltage being 5V for a given feedback resistance of 1K the opamp would saturate for a input current from photo diode of ...