Questions tagged [biasing]

The setting of the DC operating point (the DC voltage or current about which the instantaneous value might vary) of an electronic component that processes time-varying signals.

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Feeding a Reverse voltage at the output pin of an isolated DC DC converter

We have designed a Biasing card for an amplifier, In which it consists of a sequencer, a regulator to generate VG and a DC-DC converter along with Hot swap circuit for controlling the VD. I used THN30-...
39 views

How to use a negative voltage to switch betwen positive voltage and ground

Basically the title, I want the output to be a positive voltage when the control voltage is negative and the output should either be ground or open when there is no control signal (it is left floating)...
42 views

Simplest JFET front end to A/D converter

This is regarding a cheap Pmod I2S2 ADC and DAC (connected to an STM32F407G-DISC1) that uses a Cirrus CS5343 ADC. Now, as best as I can tell from the CS5343 data sheet, the $V_{PP}$ of the input ...
789 views

Why should the Vce be half the value of the supply source?

For a BJT amplifier biased to operate in the active region; I think that the statement "the voltage Vce is half the value of the supply source" is incorrect. Because I know that such a thing ...
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Noise observed in QPA2935

I am using a "Pulsed biasing board" which provides the drain signal and gate signal to a power amplifier. I am interfacing the same with QPA2935 driver amplifier(DA) Please find the ...
65 views

How to calculate the output impedance of a gain-boosted biasing circuit [closed]

I've been working on calculating the output impedance $R_{Out}$ ​of the gain-boosted biasing circuit shown in picture, where all transistors are in the saturation region. While I understand the ...
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1 vote
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Simple cascode biasing problem in an electronic circuit

use variable (𝐼_𝑅𝐸𝐹, 𝑉_𝑇𝐻,𝑉_𝐺𝑆) to express the range Assume that all 4*(W/L)1= (W/L)2= (W/L)3= (W/L)4= (W/L)5= (W/L)6 All TRs are under saturation region Assume that M2 is under subthreshold ...
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Load is switching between 0V and overcurrent in the pulsed drain biasing circuit for a Power Amplifier

Given below is a block diagram of an evaluation-board. It is a pulsed biasing board to a PA. It is designed to produce a pulsed-drain and pulsed-gate signal for the biasing of GaN Power Amplifiers. I ...
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How can we set the exact current through feedback resistor Rf1 to achieve 0V output at DC?

In this type of circuit, how can we set the exact current flowing through the feedback resistor Rf1 to set the output at 0V at <...
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Is it possible to design a circuit with an op-amp that always keeps the output voltage 1 volt higher than the input voltage?

Is it possible to design a circuit with an op-amp that always keeps the output voltage 1 volt higher than the input voltage? For example, if the input is 1V, the output should be 2V; if the input is ...
1 vote
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Bias condition of parallel silicon PN diode circuit

In the following question, D1 is operated in forward bias condition. Then the voltage across D1 is 0.7 V. Then the voltage across D2 also 0.7 V; but no current flows through D2. Then what is the ...
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Avoid cross talk between recording electrodes

I am trying to compare two record signals coming from two INA amplifiers simultaneously. Both amplifiers are actually recording the same signal, just with different recording electrodes. We are ...
151 views

How to minimize modulated signal clipping in an amplifier circuit with improper Q1 biasing?

I'm currently working on two amplifier circuits designed to process modulated signals. While the circuit on the right operates as expected, both theoretically and practically, I'm facing an issue with ...
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Transistor biasing in integrated versus discrete circuits

I have this vague sense that in the design of analog integrated circuits we tend to think of or do biasing by fixing the DC currents of amplifying stages as opposed to the DC voltages (as seemed to be ...
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Bias up and down sequence of a GaN power amplifier

I am trying to build a biasing sequence circuit for a GaN power amplifier. The GaN power amplifier I am using has a particular bias-up and bias-down sequence as shown below: The figure below is a ...
142 views

Differential amplifier op-amp schematic connection and DC biasing

I have a differential IF (intermediate frequency) signal generated by an ADL5801 RF mixer. Stage 1: the signal is amplified before active filtering and it has LC LPF in the beginning for filtering ...
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How do I choose a transistor for a VBE multiplier?

I am currently designing a 150 W audio power amplifier for 12 ohms, so 60 V peak to peak and 5 A. I'm using a C5198/A1941 pair for AB amplification with D669/B649 in a Darlington configuration so I ...
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“Undoing” the bias of a resistor

As you know, if you have an amplifier or comparator that can only output 0v to +v, you need to bias the input from -v to +v to +v to +v so that the output will produce the full signal range. But what ...
397 views

CE Amplifier problem

I am new to learning about electricity and I was trying to make a common emitter amplifier. I did some research and I tried to make the circuit. The circuit amplified the signal but the signal was not ...
1 vote
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Reducing the fall-time of a P-channel MOSFET Follow-up

The original question Answer by Simon Fitch Please refer the original question link and the suggested answer by Simon fitch I have implemented in hardware as it was recommended. I gave 15Vdc supply. ...
1 vote
182 views

Reducing the fall-time of a P-channel MOSFET

I have implemented the following circuit in hardware. My required output across load (R7) is a pulsed signal of 20 V, 100 kHz, 10% duty cycle (10 us pulse width and ON-time of 1us and OFF-time of 9 us)...
3k views

Why do we need a resistor across the transistor base-emitter junction?

I am still not very good at some of the basics. Why do we need the bottom resistor across VBE when the voltage drop is always 0.6 V (as VBE is acting as a forward bias in parallel to the resistor)? If ...
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Amplifier matching network, biasing circuit, and stability consideration

In amplifier design, it is essential to achieve proper biasing for the desired operating conditions, ensure maximum power transfer through matching, and maintain stability of the device. But, I'm ...
1 vote
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How to bias the Q55, Q54 transistors in my design (what's the right voltage value needed for it)?

I want to make a simple differential amplifier and when I bias the pnp transistor that's connected to Vcc I notice in simulation that the application is too small (less than 1) and it go around 4.96v ...
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Darlington transistor configuration

Can two 2n2222a transistors output more than 1amp of current if biased properly; supposing 1.4v to 1.5v is applied to the base?
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Electrical characteristics on datasheet

What does this part of a datasheet mean? I always get confused when studying them... Is the user suppose to meet these conditions before getting the results stated on the sheet?
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Transistor pin configuration

Is the base of a transistor (NPN) always positive or does it change due to manufacturers specs; as some might decide to put the base as pin 1 , followed by the rest; maybe collector as pin 2 etc like ...
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Do we require matching circuit and stability in Gilbert cell active mixer design? If yes then what is the procedure?

I'm trying to simulate a Gilbert cell active mixer using a PHEMT transistor model in ADS. I've referred some articles of Gilbert cell active mixer design but I haven't found any matching circuit or ...
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LTspice simulation doesn't match oscilloscope measurement; is the circuit diagram correct?

This box should add DC offset to a resonant circuit. I drew the simulation on LTspice. However, it's not similar to the result in oscilloscope. So, my question is: Is my circuit diagram correct? #1 ...
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My RF amplifier circuit works in LTSpice. Will it work in reality, too?

I am working now for a while with bias calculations. I have found a good turorial to calculate it by my own and I have seen that there are already calculators on internet, which made my life much ...
1 vote
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Impedance reflection in making a simple current source

I am making a constant current source using the transistor. I am a bit confused regarding the biasing of the transistor. I have seen in many places that when we are setting the biasing of the ...
1 vote
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Variation in a BJT's forward current gain compared to variation in saturation current

(Questions summarized at the bottom of the post.) For discrete BJT circuits, a biasing scheme like the one below is often described which helps reduce the sensitivity of $I_C$ to variations in the ...
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Wide Swing PMOS Cascode Biasing

I would like to know if someone has designed a wide swing PMOS cascode biasing circuit (as attached in the picture) in 16nm FinFET, especially for IO devices having 1.8V supply. I see that ...
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What is the basic idea behind the so-called "diamond buffer"?

The idea for this question came about after I wrote an answer to a similar question. This "diamond solution" was something unknown to me. I took a look at Wikipedia page (see the picture ...
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719 views

Class AB crossover distortion diode fix

In the class AB amplifier shown below, we use diodes to make the PNP and NPN conduct equally. How do the diodes make them conduct equally? Is there some intuition I could use to understand this ...
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Why isn't my current mirror reflecting 500uA on each side?

I'm designing a telescopic cascode with a tail current source of 1mA. I had set my VDD to be 2V and all of the mosfets in the schematic seem to be saturated but the current reflected by the current ...
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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) ...
128 views

Why is there current flowing into my JFET? [closed]

When I connect my JFET to a 9 volt battery and then short circuit the gate to the source via an ammmeter, it reads 6 mA of current. When I try biasing the JFET (BFW 11) with a 1 MΩ resistor the ...
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Biasing resistors for differential amplifier

I've an exercise where I've to design an unbalanced differential amplifier, and I'm given the circuit below and told that it's the basic one. I'm then asked to have the appropriate bias resistors. ...
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Base current in a fixed bias BJT

Why does the base current remain nearly constant, neglecting V(be) in a fixed circuit bias for a bipolar junction transistor with respect to temperature? If Rb changes with temperature, the base ...
86 views

Can I read the voltage (MCU ADC) with an isolated power source by opamp inputs?

I made a conceptual design to read an industrial 2- or 3-wire temperature sensor with a single 3-connection terminal. I used an opamp in differential mode to read two terminal connections which are ...
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How can I calculate R1, R2, RC and RE in the following silicon transistor circuit?

We have 4 unknowns, so we need 4 equations. If we make the equivalent Thévenin circuit for R1 and R2, and by applying KVL on the input and outputs we get only 2 equations. Rth=(R1×R2)/(R1+R1) Vth=(...
234 views

RS-485 bias & termination resistors with 3.3v transceiver and 100 ohm cable

I am trying to connect two boards together with a few feet of Cat 5e cable. Both boards will be using 3.3v RS-485 transceivers (ISL83483 or similar). Using this calculator, I entered 3.3v for supply ...
330 views

AC voltage on DC voltage

In the voltage divider below, the voltage at point A is obviously 5 V. If we connect a 9 V DC voltage source between ground and point A, the voltage at point A will be 9 V. I think the same is true if ...
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Which model does this equation come from in fixed bias circuit?

In fixed bias circuit I calculated voltage gain by this : I measured the DC response in simulation as: Ic = 3.73 mA Ib = 15.7 uA Vc = 11.3 mV Vbe = 824 mV I calculated re (ac emitter resistance)...
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Output voltage for clipper circuit with bias

I've been working with diodes recently and I'm struggling understanding how to actually handle them in circuit. In general, I know that they only can pass the current in one direction because of how ...
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Does collector feedback bias work like this in real life?

I am reading about collector feedback biasing in BJT transistors. Here is how it works: Now suppose for some reason, a temperature change perhaps, β increases. This should cause an increase in IC. ...
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Finding the Q-point of a transistor: disambiguation

I find the definitions of Q-point that I have been given in class to be a bit ambiguous, so please read on and confirm or correct my understanding. As I understand from this SO answer, the Q-point or ...
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