Questions tagged [amplifier]

An amplifier can be used to adapt the range of the signal to a requirement, to make it more robust for transmission, or to satisfy interface requirement (like input/output impedance)

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24 views

Understanding common-source amplifiers with resistive degeneration

I understand that by introducing the series resistance to the NMOS in the amplifier circuit the gain becomes: $$A_{v}=-\frac{R_D}{\left(\frac{1}{g_m}+R_s\right)}$$ Which means that higher values of \$...
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Need an explanation on the below circuit [closed]

I want to understand and modify the below circuit, can anyone help me by explaining this.
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Design a 2-stage cascaded transistor amplifier using a NPN BJT (both stages) with a forward current amplification factor of 90 [closed]

It must have a no-load gain between 800-1200 and must be supplied by 12 V DC. You may use any transistor configuration. Use standard resistor and capacitor values.
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Transistors in a class A amplifier

Does anyone know what role plays the Q2 transistor?
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How is the linearity of a power amplifier related to its power efficiency? T

How is the linearity of a power amplifier related to its power efficiency? The two conceptsdo not seem to have much in common, or do they in this context?
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Designing a three stage BJT transistor amplifier

My final project for my electronics class is to design a three stage transistor amplifier. I'm not asking for answers, or for someone to do this project for me. I need help starting the project and a ...
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1answer
41 views

Implementing negative feedback on a JFET amplifier

I have started designing and simulating a simple Jfet amplifier using LTSpice. The circuit I have below seems fine, apart from too much gain for my needs (about 20x to much gain). To fix this, I ...
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1answer
39 views

CS Amplifier without load or signal resistance

So I came across this interesting MOSFET question and thought I'd give it a try. I seem to be stuck on a couple of parts however, hopefully someone can see something I'm not seeing. Here is the ...
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1answer
103 views

Help with understanding transistors in circuits

The picture above is a circuit for a hearing aid, so we need sound amplification. BC547 is NPN, BC557 is PNP. How is the amplification happening, why is it connected so? Edit: I found a circuit for ...
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35 views

How would I find the gain equation for this circuit?

I can neglect the Early Effect for the BJT, and assume the capacitance is infinite. Using the small-signal AC model, I calculated $$r_e = 25 \Omega$$. My question is, how do I set up my equations/...
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1answer
59 views

What will be the Gain if the resistor value tends to infinity? [closed]

Given the circuit above, I need to find the expression for gain if the r_pi tends to infinity. my question is will v_pi still be v_in?
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Analogue signal issue?

I have an issue with a analogue signal. Your help would be greatly appreciated. The signal is a 5Vdc, it is an output from a PCB which is a source to many A/D PCB. its output is connected using wire ...
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1answer
67 views

How do I calculate the wattage of a set of speakers?

I've just received a set of speakers that I want to design an amplifier for. Two of them are 5W 4Ω and one of them is 10W 8Ω. How do I find the total peak power output of these? I apologize for such ...
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What is the difference between these CE amplifiers? (Why we use op-amp in this CE amplifier circuit?) [closed]

Above image is Common Emitter Amplifier - (Circuit 1). And above image is another Common Emitter Amplifier using operational amplifier (op-amp) - (Circuit 2). This image is Simulation Result of ...
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Misunderstanding of calculating gain of amplifier

I’ve been reading in my textbook that the gain is Gain= Vout/Vin= 1+ Rf/Rin However, what if there isn’t a resistor like this amplifier? Would it be 1V/V or 2V/V? Or am I totally misunderstanding this?...
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51 views

Problem in microphone circuit

I've placed the circuit on the breadboard and found an unexpected low-frequency noise appearing again and again. The computer microphone doesn't show this type of distortion. But my circuit is showing....
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Piezo signal amplifier using LM358 opamp

I was trying to amplify the signal of a piezo, which is very low and amplify it so that I could use it to latch a flipflop. I had the LM358 opamp so I made a differential amplifier by a gain of 50 so ...
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Would we like to have a linear circuit application to cause low distortion at the output port?

Would we like to have a linear circuit application to cause low distortion at the output port? What about a power amplifier? Is it necessary for a power amplifier to have only low distortion at the ...
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1answer
56 views

I want to understand this audio input to LED output simple circuit

I'm a newbie in electronics. I watched a youtube video that showed how to activate LEDs using a microphone. It's project #3 at https://youtu.be/zsJ61yJhWVU?t=115 The guy built the circuit on camera ...
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1answer
59 views

Circuit voltage / amp calculation

I am new to electronics (using Arduino), begging to venture into creating my own circuits and not following set example. I would appreciate advice on the following. When deciding upon how to power a ...
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1answer
60 views

How does the Common Emitter amplifier ensure low distortion?

My understanding of a small-signal amplifier is very limited. From what i've understood from this article is that for a BJT in the CE configuration, it provides minimal distortion at the output, I ...
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45 views

How to improve emitter-follower efficiency?

I’m trying to wrap my head around the emitter follower. I’m currently using it to simulate a ~12V AC coming from a intercom ringer (about 700Hz). simulate this circuit – Schematic created using ...
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2answers
35 views

Amplifiying PWM signal to 10v analog

I have a 5V PWM signal around 500Hz. I want to have 0-10V analog output from this. I considered using a MOSFET to step the 5V PWM to 10V PWM and using a low pass filter at the output to achieve my ...
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2answers
90 views

How is this pole compensated

I have an amplifier in a closed loop, the diagram looks as follows: The DC gain is simple which \$ -Rf/R1 \$. If I make \$ -Rf=2\cdot R1 \$ the the DC gain is two. This is verified using AC analysis ...
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Voltage-divider bias common emitter calculations are yielding unexpected results

I performed an analysis on this voltage-divider-feedback common emitter. My result in simulation is relatively close, but doesn't quite check out. Where did I go wrong? I'm new to this and ...
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1answer
56 views

Purpose of resistor in pre_amp circuit

Trying to understand this circuit. What is the resistor R1 for? Wouldn't it just continuously supply voltage to the base and make it always "ON"? Another version:
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Cascading common emitter and common collector

I am trying to design an amplifier for a 1 W 8 ohm speaker for educational purposes. The idea is to start from a common emitter amplifier to amplify voltage and then add a common collector (emitter ...
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67 views

How do I perform ac analysis of common emitter with voltage divider feedback?

I'm working towards understanding voltage-shunt feedback. I'm about halfway there, and stuck. I am building a simple common emitter with voltage divider feedback. I managed to get it biased to put ...
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Location of Amplifier for Signal Integrity

Let's say I have a photodiode that outputs a current with respect to incident light on the die. If this photodiode will be located 12 inches or so away from the control board, would it be better for ...
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95 views

Trying to obtain a voltage gain equal to 3 without an op-amp

I'm a beginner in electronics and currently, I am trying to design a Wien bridge oscillator. I've read documents about oscillators. For now I am stuck at trying to design the amplifier, without using ...
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How can I get rid of the noise from this audio amplifier (using a Kemo M031N)?

I am trying to wire up an audio amplifier circuit using the Kemo M031N 3.5W amplifier: I have connected the wires from the amplifier to a terminal block. With a suitable 10V power supply and a 2W ...
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How to connect a load to an amplifier without a loss in gain?

I have this circuit below, that represents a common emitter amplifier: When connecting a load of 10 ohms to the collector node and a signal to the base node there is a huge loss in the gain of the ...
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Effects of bootlace ferrules to connect load-cell with amplifier

My colleague and I had an argument about whether or not to use bootlace ferrules for a load-cell (4 stranded wires + 1 shield | 100mg precision | OIML C3 | max. 3kg) going into an amplifier (spring-...
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1answer
109 views

NUCLEO-G031K8 ADC conversion for audio recording — bit resolution and recording quality

I am planning to use NUCLEO-G031K8 board as an audio interface for my electric guitar to computer. So I designed a circuit to amplify small signal of guitar. When I check board's datasheet it is ...
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How do you find rO when solving this differential amplifier?

gm could be determined using Jacoletto (40*Ic, where Ic was found while solving the bias point)? Some of my attempts at solving the circuit
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What unit is expressing the effect of this capacitor in a common emitter amplifier?

I'm working through this handout I3.PDF in my attempt to understand negative feedback in amplifiers. The following formula appears, in which the author is substituting \$v_{out}\$ and \$v_{in}\$ to ...
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1answer
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Stability analysis of cross-coupled amplifier in Cadence

I am trying to implement a cross coupled amplifier with OP-AMP feedback. I am not able to get it stable for a square wave however. The circuit looks as follows: The OP AMP is ideal from Cadence, all ...
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1answer
42 views

I designed a 4 Resistance biased amplifer, I used the Voltage divider MOSFET amplifer circuit for 2N7000

The blue lines in the simulation are the output and the green lines are the input, So I designed this amplifier while trying to limit Id to 200mA and I wanted to Bias the MOSFET such that I get no ...
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1answer
92 views

I am designing a 2 resistor MOSFET amplifier but the output is generating square waves

I am learning about MOSFETs and I was tasked to design a 2 resistor biased amplifier. This is what I came up with. I am really not sure what a 2 resistor biased amplifier is, could someone please help ...
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1answer
58 views

How do I compute the gain on this differential amplifier (in an open loop)?

Hello! I've got this project due for a college course, and the teacher has reviewed my work and said that it is within specification, but he asked me to compute the gain the good old fashioned way ...
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76 views

Audio jack acts like an antenna?

I am using a simple pre-amplifier circuit for an electret microphone. Here's the schematic and the AC transfer function: The output is connected to a 3.5mm audio jack through a couple of half a meter ...
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1answer
57 views

Calibration of response of A preamplifier : LTSpice

I would like to calibrate my electronics. Row signal is something like pulse-A, width is 40nsec. When I input this signal to preamplifier, output is something like pulse-B. I would like to calibrate ...
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2answers
103 views

Homemade GPS Receiver: Cascading LNAs and Band-Pass Filters?

Over the last couple of months, I developed a software-defined GPS receiver. Unfortunately, it's not very sensitive, and can only detect very strong satellite signals. For the RF front-end, I am using ...
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2answers
103 views

Upper 3-dB frequency of differential amplifier with current mirror load vs with resistive load

In the BJT case, why is it that the upper 3-dB frequency of a differential amplifier with a current-mirror load (1st picture) is lower than that of a differential amplifier with a purely resistive ...
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54 views

Pre-amplifier gain issues

I built a 2.1 subwoofer circuit. The schematic is below. The problem is the sound is low volume. It should be louder than this. I want to confirm the coupling capacitor values are ok in every ...
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20 views

Strain gauge measurements with carrier frequency

In near future, I would need to do strain gauge measurements using HBMs instruments, the amplifier will be MX1615B. In my case, the gauges will be placed near a 50Hz gearmotor and run with VFD. As far ...
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1answer
53 views

Measuring RMS power output from audio amplifier channel

I am looking for a simple way for getting the RMS power output of an amplifier channel set to some arbitrary gain. I want this in order to find the maximum level I can safely set the amplifier at for ...
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39 views

Question about local NFB in a transistor

I've seen this a few times and I can't seem to find documentation so maybe I'm not understanding what's happening here. My interpretation is that the transistor is configured as a common emitter and ...
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1answer
44 views

Long-tailed pair LTspice simulation

I have been having some trouble designing a long-tailed pair transistor amplifier. Vdd2 is 5V and the 6.8k ohm resistors were already given. I am trying to get a bias voltage of 0.8V at the transistor ...
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38 views

Voltage gain of BJT CE stage amplifier

The question is to calculate the voltage gain, V_out / V_in in terms of small signal parameters and R_C. (Ignore Early effect) First I made a small signal circuit for it, and found voltage gain. But ...

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