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Questions tagged [bias]

A DC voltage or current in a circuit to set the operation point of an active or non-linear component.

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Please provide your comments on this circuit idea of mine for bias generation?

There is a requirement for a P-side current generation. Currently we have P-side Vt/R solution which is the left branch in the figure, except it is diode connected. When the PMOS is diode connected, ...
user124713'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 ...
lemon's user avatar
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AC analysis of a Bias Tee

I am designing a bias tee here and wondered whether it actually works or not? Hence I conducted an AC analysis instead of S-parameters (after verifying that s parameters are okay). The bias tee has ...
Curious Cosmopolitan's user avatar
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Solid-state relay input characteristics

I am a bit confused by some of the specification on this solid state relay LD00KM. I am looking at the case in which this relay is used in the 2 Terminal Input (Direct Drive) Configuration as shown in ...
Gman's user avatar
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Biased Clamper Circuits

I have been tasked to design a clamp circuit to clamp the negative extreme of a periodic input waveform to −5 V. I can use diodes, zener diodes, and resistors of any values required. I will assume a 0....
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DC Bias network for a LCR meter

I am trying to make a DC bias network for my LCR meter (Scientific SM6023) based on this circuit I found online RD10E has a Zener voltage of about 10V and 1N4004 has a forward voltage of 1V. I have ...
amogh waghmare's user avatar
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Direction of Op Amps Input Bias Current relative to declared sign on datasheet

Input Bias Current is a parameter of Op Amps related to the Base/Gate currents flowing in or out of the differential amplifiers at the input of the amplifier. It is calculated as the average value of ...
Ricardo M.'s user avatar
1 vote
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99 views

Non inverting opamp with bias DC

I'm doing a lab work on a circuit that takes a square signal in the input and first amplify it, then shape it and the amplify it again. So the circuit is actually composed by: an amplifier (inverting),...
Gabriele's user avatar
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Can a capacitor be used for biasing?

I have a load switch IC SiP32431DN which internally has a comparator at its input stage (connected to its on/off pin). If I connected a, let's say, 100nF capacitor to this on/off pin, would that be ...
trevor's user avatar
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Instructables DIY current limiter circuit [duplicate]

I found this inline and was hoping if that circuit is okay. Instead of a battery though, I want to use a dynamo (plenty of juice-wise). Output of dynamo is 18 V 200 mA. I wish I could adjust the ...
imran muhd's user avatar
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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 ...
gooseggs2976's user avatar
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MAX9924 input signal and bias?

I'm trying figure out how to connect a MAX9924 ("Variable-Reluctance Sensor Interface with Differential Input and Adaptive Peak Threshold") to a sensor on a rowing machine. My knowledge of ...
mho's user avatar
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Vintage Intercom BJT Preamplifier: Purpose of Capacitors and DC Bias Troubleshooting

EDIT - Further Research - Comments on Common Emitter Preamplifier https://sites.google.com/a/davidmorrin.com/www/home/trouble/transistors/amplifiers The preamplifier stage in the circuit below has ...
SystemTheory's user avatar
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Stability factor and stiffness of voltage divider on a transitor

Does stability factor and stiffness of the bias network have a connection? this site mentioned something about stability factor so i was wondering if its thesame thumb rule about the current in ...
imran muhd's user avatar
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Highest DC current gain

I drew a circuit with a transistor (ktc3198) at heart for getting the highest DC gain the transistor can offer. I used its input and output characteristics. And based on that I made a little circuit. ...
imran muhd's user avatar
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Biasing using output charesteristics of a transistor

So this is output charesteristics of a transistor (ktc 3198)with variying base current values. Is it okay to design a voltage divider bias with output charesteristics as reference?
imran muhd's user avatar
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Having trouble understanding op amp purpose

I came across an op amp circuit in a paper I am reading. The paper says it is supposed to be a 2.5 V dc offset, but I can't find a way to confirm that. I tried replicating it in LT Spice, but it doesn'...
user1402154's user avatar
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Q point and dc biasing

For a proper dc current gain, how do i choose a proper q point without getting the transistor into saturation or cutoff using voltage divider bias technique?
imran muhd's user avatar
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DC current gain [duplicate]

Does this graph provide information about the current gain of a transistor? (KTC3198)
Ruqayya Saleh's user avatar
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296 views

DC current gain of transistor

I'm having a little thought about how DC current gain comes about. If Ic = Beta x Ib, does that mean the current flowing through collector to emitter and the current from the base i.e beta x Ib is ...
Ruqayya Saleh's user avatar
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VBE of BJT keeps increasing beyond 0.7V, Why is it not getting saturated around 0.7V?

Background: I am trying to understand the progressive steps to the final current limiter mentioned in this site. As a first step, I am checking the effect without the feedback loop: Why is the VBE ...
Dynamic_equilibrium's user avatar
-1 votes
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Base resistor R2 for voltage bias [closed]

Can someone please explain to me how they arrived at 38.8k ohms for the R2 from this site, under the voltage divider bias technique... I just can't seem to figure it out. Pls help out voltage divider ...
imran muhd's user avatar
2 votes
5 answers
701 views

Vb and Vbe of a transitor

Is VB and VBE, of a transistor the same? If not, how is Vbe generated? ....and must the base voltage of a transistor be equal to 0.7 or can it exceed this value.
imran muhd's user avatar
2 votes
2 answers
552 views

Formula for R1 and R2 of a voltage divider bias

Please I'm asking if the stated procedure for R1 and R2 of a voltage divider is correct i.e if its valid way to come up with their respective values. If so, how do interpret the two statements ...
imran muhd's user avatar
1 vote
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Biasing AC signal - which circuit is the best?

I've seen a similar question asked earlier here: How do I bias an AC signal for sampling? However, I have a 3 different circuits and I am not sure which one works best! I have: +-2V AC signal of ...
L'orealMenExpert's user avatar
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Bjt q point graph

Please what does this part of the graph represents?
imran muhd's user avatar
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BJT DC biasing and amplification

Does this part of the datasheet has to do with biasing and amplifying DC using BJT (TIP120)? [!tip120 datasheet]2
imran muhd's user avatar
1 vote
1 answer
211 views

How to choose components to design a bias tee

How can I choose components to design a bias tee? What impact do the inductor, capacitor and resistance have on the circuit?
zedacky's user avatar
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232 views

Un-biasing transistors

To amplify small signals, NPN BJT must be operated such that Vb + VsigLowest must be greater than the voltage drop of Vbe (~0.7V). How do we center the resulting voltage Vce around 0?
rjpj1998's user avatar
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Gate bias voltage in class C amplifier

Question How should the gate of the MOSFET be biased to achieve maximum efficiency (in class c amplifier), when gain is not important? Explanation On the one hand, in the tutorial (link) it is shown ...
piotr's user avatar
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1 answer
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Summing up transistor gains [closed]

I was wondering if its possible to sum up transistor gains.
imran muhd's user avatar
-1 votes
1 answer
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Darlington Amplifier circuit (TIP 120) [duplicate]

I'm trying to wire a darlington TIP120 just to see if I can get the 1000 hfe dc gain at 100mA like it said on the data sheet. I made the circuit like it appeared in the data sheet, but wasn't ...
imran muhd's user avatar
1 vote
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What kind of bridge circuit is this?

While I was analyzing the old Tektronix' sampling oscilloscope, I found the above circuit that is adjusting the bias voltage of the sampling gate diodes. I understand its purpose, but could not ...
Emm386's user avatar
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Advice on simulating amplifier and power splitter circuit in LTspice

I am using LTspice to simulate an AC resonant circuit that should amplify and split an RF signal. I would like to add small circuit to it, so that it should add a DC offset to the original circuit. ...
Nana's user avatar
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Bias common mode and Impendence in relation to ASD1299

I was wondering if anyone would be able to help me understand the Bias common mode and Impendence in relation to ADS1299. If someone has a ADS1299 for dummies that would be great Thanks
danny's user avatar
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Why does IMU acceleration bias increase with increase in acceleration?

I am trying to estimate the wheel speed scale factor of a vehicle. I find that whenever the vehicle accelerates rapidly,the estimated speed is lower than the true speed. In other words, I see bias in ...
user146290's user avatar
1 vote
1 answer
99 views

Biasing a BJT in a common emitter amplifier

I'm trying to design this common emitter amplifier to have a Q-point of \$(V_C=2.5 V, I_C = 2.5 mA)\$. According to my calculations (see below), if I were to use \$R_2 = 100 k\Omega\$, I should also ...
kene02's user avatar
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Bias for single supply OA

simulate this circuit – Schematic created using CircuitLab I am supplying an audio circuit with only a positive voltage of 12V. I have created a mid point (aka virtual ground, aka bias...) of ...
Status Re's user avatar
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3 votes
3 answers
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Understanding biasing typologies of a class AB amplifier

I've been trying to understand how the biasing of a simple class AB amplifier works and I've encountered a few comprehension issues. Here's the simplest way I found to bias it: If we apply kirchhoff ...
tampler's user avatar
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1 vote
3 answers
259 views

How to sense a wide range of voltage and output a certain voltage?

I have an input voltage of 0-400V DC, I want to sense the input voltage as low as 100mV and output 5V and if voltage is lower than 100mV then output 0V. I know it can easily be done with an op amp but ...
ElectronSurf's user avatar
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1 vote
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JFET self bias-configuration quiescent point calculation

I am learning JFET biasing configurations. For self biasing configuration (circuit below), the quiescent point is determined as the intersection of the following equations(1) - ...
tinkerbeast's user avatar
2 votes
1 answer
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Bias current of a MOS differential amplifier using two transistors

I am trying to understand the role of M14 and M13 transistors in the paper "Compact silicon neuron circuit with spiking and bursting behavior" by Jayawan H.B. Wijekoon, Piotr Dudek (2008) ...
Little Rocket Guy's user avatar
1 vote
3 answers
228 views

Bias voltage in non-inverting op-amp topology being pulled down

I decided to quickly put together a circuit today but found an issue that has sometimes happened when making circuits with TL072. Briefly, the circuit is a non-inverting amp with about 34dB gain in ...
CouchAnalysis's user avatar
6 votes
3 answers
1k views

What is the purpose of these passives in a microphone pre-amplifier circuit?

This is the typical application circuit of the MAX4466 "microphone preamplifier" op-amp. Are these resistors/capacitors purely for generating a bias voltage? If so, aren't there much simpler ...
laust0rm's user avatar
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PNP: What happens if the base voltage is higher than the emitter voltage?

Can a PNP transistor switch a 5 volt load such that in the off state the base is supplied with 12 volts and the on state is pulled to ground (Vb > Ve)? I remember hearing that the base voltage ...
KJ7LNW's user avatar
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Op-amp current values

In this App note, page 7, example 3, can someone tell me from where the values for IBN and IBI are coming from? I.e. \$I_{BN}\$ = -(5 nA + 0.5 nA) \$I_{BI}\$ = (5 nA - 0.5 nA) I'm using this MCP601 ...
user avatar
4 votes
2 answers
219 views

Ideas why this operational amplifier could have worse bias stability than anticipated

Background Below is the simplified schematic of an operational amplifier I tested. I left out compensation components, because the question is about the DC behavior only. The design has sufficient ...
tobalt's user avatar
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8 votes
6 answers
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Effective capacitance of a capacitor under DC-bias voltage

In my system, I charge a multi-layer ceramic capacitor between 3 V and 5 V using a buck converter. Once the voltage reaches 5 V, the capacitor starts discharging until it reaches 3 V, and the cycle ...
shakingwindow's user avatar
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1 answer
259 views

Bias tee in Vector Network Analyzer

Can I use a bias tee in the back of a VNA (E5080B) as a port 1 and 2, or do I need a mixer for it? I want to measure the network parameters of a device that requires bias.
Ferrofluid's user avatar
2 votes
1 answer
125 views

Why are the op-amps' positive inputs getting biased to -3.8 V in this differential probe circuit?

My students built a differential probe circuit, basically following this circuit from Hackaday shown below: For U1 and U2 they instead used MAX4104ESA+ op-amps. The op-amps are supplied through +/-5 ...
M. Matthias's user avatar

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