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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20 views

Gate voltage range - Biasing circuit

I am looking for Biasing circuits which can provide gate voltage in the range of -4V to -0.5V. In the application note of AMPLEON AN-11130, there is a table mentioning the specifications of the ...
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32 views

XSYSTOR - biasing circuit [closed]

I am exploring for various biasing circuits for power amplifiers. I found XSYSTOR. I am very much interested in their evaluation modules 600 Series. I need the schematic of the same. I tried to ...
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93 views

Choosing the right opamp for biasing a square wave

I am trying to bias a 1MHz, Vpp = 1V, bipolar square wave signal coming from an opamp. I want to bias it by 1V, the 1V bias (Vcm) is available at an ADC's output port. I am thinking about using this ...
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30 views

Please explain negative bias and “a stronger field to sweep carriers out of depletion”

I want to understand what a comment means, and I couldn't ask in a comment. In this question, someone asked why use an op-amp with a photodiode rather than just a resistor. The answers and comments ...
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35 views

What is the correct way to bias a floating instrumentation amplifier?

Im designing a voltage measurement circuit that needs to measure differential signals in the order of mV in the presence of high voltage common mode noise. Im using a isolated DC/DC converter that is ...
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1answer
142 views

Where do input bias currents flow and what voltage drops do they create?

I have asked this question (and answered it below) mainly as a continuation of the question, How does the compensation resistor in an inverting amplifier compensate for the input bias current?... but ...
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1answer
76 views

Single supply amplifier biasing

I'm trying to understand this circuit. I can see that BW1 is a low pass filter and BW3 removes any DC from the output signal, but what does BW2 do? If it is acting as a filter, is it a high pass ...
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27 views

How to calculate neutral base width for an emitter-base junction with forward bias voltage

I am trying to find the neutral base width for an emitter-base junction with a forward bias of 0.75V and a base-collector junction reverse bias of 20V. I am not sure how to factor in the forward bias ...
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3answers
213 views

Suitable bias resistor for microphone with higher voltage source than microphone's rating

I have headset microphone with a rated impedance of 2.2Kohm, that according to the data I've been able to find for it can be powered by 1.5 to 10v. I do not know what the maximum current is, ...
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52 views

Does the bias amplifier of the RLD amplifier need to be connected to reference electrode of the measurement sensor?

I am using the MyoWare AT-04-001 muscle sensor and FSR400 force sensing resistor sensors with the ADS1299 amplifier and ADC and I need to improve the CMRR. The datasheet mentions that an RC filter ...
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328 views

Biasing circuit - Voltage follower circuit

I am using MABC-001000-DP000L, which is and Bias controller/sequencer. I am using this for Providing gate voltage and drain voltage to the power amplifier. In the datasheet, it is mentioned that the ...
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68 views

Biasing circuit schematic - MABC-001000-DP000L [duplicate]

I am trying to design a bias controller circuit using MABC-001000-DP000L. I am unable to find the full schematic of the same. Has any one used MABC-001000-DP000L for designing bias circuit? Edit:- I ...
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Design of bias-T (L band,10 MHz,DC)

I want to design a bias-T for satellite application where L band RF (950-2150 MHz),10 MHz, and DC will be multiplexed. I need help in finalizing/selecting the inductor(choke) through which DC (13V/18V,...
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2answers
33 views

Biasing network for phototubes and photomultipliers

I have some doubts about typical biasing network for vacuum phototubes and photomultipliers. Precisely, let's start by a simple photocathode. I have seen some biasing network like this one: In this ...
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3answers
66 views

Why does the bias decreases in this clamper circuit?

I'm trying to do a positive clamper circuit in easyeda.com to bias a triangular signal of 200mV pk-to-pk at 1kHz centered around 0V. Here's the circuit: The bias seems to work only during the first ...
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1answer
38 views

Bias T with pulse train

I want to bias my pulser output which is 0 to 30V pulse train. (Which means I want to make 30 to 60V pulses) First, I used a bias T with 30V DC input: I found that it works as a differentiator which ...
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1answer
49 views

How can I find the power provided by the battery?

simulate this circuit – Schematic created using CircuitLab How can I find the power provided by the battery? I've calculated the operation point: Vce(Q1): 8.12V IC(Q1) = 1.63 mA Vec(Q2): 6.25V ...
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2answers
133 views

Source Resistor of JFET Source-Follower

I am designing a simple Buffer to get the voltage of a high-impedanze source to an ADC (60k Impedance). For that I choosed an JFET in the source-follower configuration. simulate this circuit – ...
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7answers
324 views

Why do we need 4 resistors for a common emitter amplifier?

I'm studying the 4 resistors bias configuration, I'm trying to understand why we need everyone of these resistors. If I understood correctly, Re is used to make the Q-point stable, while R1 and R2 ...
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2answers
117 views

How does this BJT biased with a diode work?

I'm trying to teach myself some basic electronics and I'm stuck on understanding what's going on with this simple NPN transistor circuit that is using a diode for bias. I've simulated the circuit ...
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1answer
62 views

How can I choose the resistors for a push-pull class AB amplifier (diode biasing) to get a certain bias current?

Hello guys, this is my very first question. This is a part from a BJt audio amplifier volume control with 3 stages (Pre-amplifier,Buffer, & Power amplifier). This is the power amplifier stage. I ...
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3answers
74 views

Opamp input bias current and current sources

I have a current source connected to a load and I want to measure the voltage at the output of the source, and therefore I would like to buffer this voltage. In this configuration, I am under the ...
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1answer
82 views

How does a transistor work as a switch; internally what actually happens?

I have searched about this, and wherever I see they mention two things: How [the transistor] will be biasing Q-point must be at the cut-off and in saturation. But I want to know in the case of the "...
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1answer
24 views

Bias Input Current Compensation for Instrumentation Amplifier

What is the motivation to choose R1=R5=5k6 Ohm? If they are for bias current compensation and both OP Amps have same Bias input current, 10k should be taken in my opinion to eliminate common mode ...
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BJT conceptual doubt

I was given this problem in a problem set. I want to ask what will the voltage at Base when \$ \beta \rightarrow \infty\$. My answer to the problem - When \$ \beta \rightarrow \infty\$ then width of ...
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3answers
127 views

Common emitter with input connected between the voltage divider and base

Similar questions have been asked before, however they don't really answer what I'm actually looking for so I asked a new question instead. TL;DR Why does the circuit below cause noise at the output? ...
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45 views

Vbe multiplier current sense controlled

Using a classical amplifier output stage (whatever it is), is there a Vbe multiplier (rubber diode bias circuit) that allows you to adjust the current through the sensing of the power resistor of the ...
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2answers
48 views

maximum collector-emitter voltage in BJTs

I am reading BC817 datasheet. According to the datasheet, maximum collector-emitter voltage at open base condition is 45 V. In typical applications we don't use open base configuration. My question is ...
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46 views

BJT voltage divider bias problem

Hi I am having trouble with how to find Req of the resistor network of the bjt circuit on the schematic. How can I calculate it to find Ib Vb values? thanks.
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1answer
102 views

Reducing the number of expensive capacitors in an audio opamp circuit

I'm designing a guitar effect (simple booster) which uses a CD4053 cmos switch as outlined here (http://www.geofex.com/Article_Folders/cd4053/cd4053.htm) As you can see from the second diagram, RG ...
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1answer
106 views

Why are there three transistor pairs in Class B Power Amplifier circuit?

I have a Class B amplifier circuit to be done in lab. Why three pair of transistors are used in this? I suppose one is a Darlington pair but what is the requirement of the third one. Also, why there ...
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7answers
1k views

Emitter resistor and biasing voltage

In many articles regarding transistor biasing I see a circuit like below and I don't really get what is the point of biasing like this WITHOUT emitter resistor Re? When emitter branch is connected ...
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2answers
54 views

How to bias an AC signal correctly?

I have an AC signal and want to give it a new DC offset. There are some questions about my experiment results. (The original signal bias and terminal output bias are the same because I want to know ...
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1answer
94 views

Stuck on designing a simple CS Amplifier

I am trying to design a common source amplifier and getting stuck during the design process. Was wondering if anyone can help me out. Ill show my process with comments and if anyone can show me the ...
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1answer
71 views

Autobias Vbe with output current sensing

this is a question about analog audio amplifiers and automatic regulation of the output stage bias circuitry. I basically need to implement an autobias circuit on this output stage topology: As you ...
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2answers
288 views

Howland current source with voltage reference [closed]

I need a precision current pump for small ac signals(50uA) and i tried it in multisim with a howland topology. It works however i need the load to not be grounded but bound to a bias voltage. Here i ...
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42 views

RF GaN transistor biasing

I am trying to understand the difference of pulse operating. How I get there is two ways. For example. Bias procedure: Set \$I_D\$ limit to 400 mA, \$I_G\$ limit to 4.5 mA Set \$V_G\$ to -5.0V ...
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2answers
155 views

Sampling a +/- 12v signal with a 0-3.3v micro pin

It's been ages since I've had to use my old school notes. I am trying to get an esp32 to read an analog voltage that ranges from -12 to +12. Obviously, the 3.3v esp32 won't like those voltages so I ...
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1answer
67 views

Applying Ripple to a DC Source?

I have a system that is powered by a 25V Lithium ion battery pack. I need to test the system with a 1 Vpp sine applied on top of the 25V supply, so 25V +/- 0.5V ripple. I know theoretically to get ...
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1answer
130 views

Active RF Antenna power PCB layout: where to place the inductor for a bias tee?

I have an active RF antenna that is powered through an inductor in a bias tee network. How should I draw it on PCB layout? I have 3 ways to do that. In these layouts, up is capacitor, bottom is ...
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1answer
88 views

How to calculate current sink

Below schematic is what I have on the breadboard: simulate this circuit – Schematic created using CircuitLab R1 is there to sink 10mA of current to bias LM317, but 470 ohm is a value that I ...
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1answer
65 views

Bias voltage of transistor [closed]

I would like to understand the purpose of biasing the transistor and why It has to be halfway between Vcc and ground? And which terminal of the transistor (Base, collector or emitter) should be ...
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1answer
81 views

What does Bias Repeatability tell me in an IMU's spec sheet?

If there is a standard interpretation of bias repeatability as it applies to a gyroscope, what is that interpretation? This document indicates that it represents the average change in bias between ...
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1answer
34 views

Forward and Reverse Bias regions for voltage versus current of diode

Below I have the graph of the voltage of a diode versus its current. As you can see, the forward bias region is when Vd>0 and reverse bias when Vd<0. My question is: In which region does Vd=0 fall ...
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2answers
112 views

Reduce minimum operating voltage of an H-bridge

I have purchased the following H-bridge and I'm controlling it with a microcontroller: https://www.amazon.com/H-Bridge-Brakes-Forward-Reverse-Full-Duty/dp/B07GFFVZKS My problem is that the MOSFETs ...
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2answers
180 views

JFET Vgs Calculation Equation

Does anyone know the formula to calculate the Vgs of a JFET used as a variable resistor? Say, I have a Vds of 24v and I require a current of 20mA (just arbitrary values) I would need a 1.2k resistance,...
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5answers
1k views

Isolated audio without a transformer

I'm putting together a guitar pedal for splitting the signal to two different amps. One of the features I want to put in is a 'ground-lift'; isolating the signal to avoid ground loops between the two ...
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4answers
1k views

VBE Multiplier with Emitter Resistance Cancellation

Function of shown circuit is biasing of output power stage complementary audio amplifier. P1 allows precise adjustment of \$ V_{CE} \$ of VBE multiplier and \$C_B\$ improves its rail rejection. \$ r_e'...
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146 views

Several questions on video circuits

Part 1: Looking into several old good home computer video output circuits I see the similarity I can not fully understand. They use diodes or transistors as a bias for the final output section. See ...
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193 views

Applying a 1/3 bias to an LCD display spec'd at 1/2 still safe?

We're currently using an MSP430 with an integrated LCD controller that only has a 1/3 bias mode. The LCD display has a 2-mux configuration and the data sheet specifies "drive method: 1/2 duty, 1/2 ...

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