Questions tagged [amplifier]

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

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4 answers
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why is transformer not considered as an amplifier?

I know that in a transformer the power is conserved on both sides, and hence there's no power amplification as such. That's fine! But if I instead want only a voltage amplification, then choosing ...
-1 votes
1 answer
43 views

How do I design a Multistage Amplifier with given specifications? [closed]

I have been tasked to design a multistage amplifier with the following specifications: Gain(V/V) = 30, Rin = 20 kohms, Rout < 25 ohms, Power supply = Dual +12V -12V, Max Symmetrical Swing > 9Vpp ...
1 vote
1 answer
42 views

Why did my transistor break down? (Common Collector Amp)

I've designed a simple common collector circuit (see picture) and tested it into an 8ohm dummy load and everything seemed fine. So I connected the output to a speaker and the input to my laptop and ...
0 votes
0 answers
39 views

cascode NMOS (virtuoso)

I have run across a problem. When I was trying to design a cascode amplifier that was gain>=10V I have succeeded to make it. The rout in gm/Id method is 1.58M ohms. When I typed the width and ...
0 votes
1 answer
245 views

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 ...
-1 votes
0 answers
39 views

Can 360 Step Down do Inverting voltage? [closed]

So I've been using LM2596 as my negative voltage reference, and now i'm looking for easy to find, super small, and cheap component that i can use to do inverting voltage. Is it possible to use this ...
6 votes
2 answers
351 views

Why is the frequency and voltage of my Colpitts oscillator lower on breadboard than LTSpice?

My colpitts oscillator I made on LTSpice oscillated at 5 MHz at a peak-to-peak voltage of 260V. When I put all the components down on my breadboard and measured it with a real oscilloscope, the ...
0 votes
1 answer
425 views

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 ...
2 votes
5 answers
124 views

Stages of audio amplification from mV to 20V+

I have been trying to learn how to amplify audio signals from very small signals (20mV) to large signals (20V+) while using only transistors. I have figured out how to build a class A common emitter ...
0 votes
1 answer
61 views

RF coupler to measure output of PA

I want to build a RF coupler in order to measure harmonics after the low pass filter board of my shortwave PA. I have a dummy load that can handle the 600W output of the PA. And I have a tiny SA to ...
0 votes
1 answer
137 views

Transimpedance amplifier with OPA838 - oscillation - supply voltage

This post is the continuation of my previous post: Transimpedance amplifier with OPA838 - instability Considering there were a lot of discussion, so we made this new post, to add for details, such as ...
4 votes
4 answers
1k views

Why is a peak in the gain a sign of instability in a closed loop op-amp circuit?

I watched a tutorial video that mentioned that when there is a peak in gain (dB), it is a sign of instability in the op-amp circuit. Is this statement always correct? If yes, can any one please ...
-2 votes
0 answers
70 views

need help understanding schematic [closed]

I'm relatively new to the world of electronics, and I've stumbled upon a schematic diagram that's been giving me quite a headache. I was hoping some of you experienced folks could lend me a hand in ...
0 votes
0 answers
45 views

The effect of input and output impedance

This picture shows the classical feedback system and this assumption about this system. "the input impedances of both the amplifier and the feedback network are infinite and their output ...
4 votes
2 answers
293 views

Three-stage CE-CE-CC Amplifier [closed]

I am designing a three-stage amplifier to produce an output Vout that will deliver 100mW rms power to an 8-ohm load, for a sinusoidal input of 10mVpk 1 kHz with a signal resistance of 500 ohms. It ...
0 votes
4 answers
2k views

Guitar Amplifier Peavey Backstage Plus

The fuse of this guitar amplifier blows. Changing the output transistors had the amp working for a while, but then after a while the fuse blew again. The output transistors that were changed are new. ...
0 votes
2 answers
328 views

Instrumentation Amplifier Reference Node - Integrator vs Buffer

When looking at INA topologies (lets take AD8220 for example) I see examples of integrator or buffered resistor dividers used. What are the disadvantages of using an integrator? Both typologies ...
1 vote
1 answer
446 views

Accuracy when measuring THD with LT Spice for AB Audio Amp

I've designed and built my own AB class audio amplifier circuit. I designed it to have as low THD as possible, using LT Spice to run my simulations with the .four command, so I created a bunch of ...
3 votes
2 answers
396 views

How to share a single gain resistor among multiple op-amps in a circuit

I'm currently designing a circuit where I need to implement multiple op-amps, each configured with the same variable gain resistor using a single digital potentiometer. To simplify the design and ...
3 votes
2 answers
106 views

Operation explanation of a low-swing differential receiver (amplifier)

The following figure shows an example of a low-swing differential receiver given in Hall's Advanced Signal Integrity for High Speed Digital Designs However, I cannot figure out how this circuit works ...
4 votes
1 answer
210 views

Measuring integrated current

I want to measure the amount of light striking a photodiode in a specific time window (about 1ms). In this window, we get \$10^6-10^7\$ photons, which get converted into electrons with about 80% ...
3 votes
3 answers
216 views

Help me understand this high voltage amplifier circuit

This question is about the circuit which also present in here: Help me understand this high voltage amplifier circuit for driving a piezo actuator I have some follow up questions: What is the reason ...
1 vote
5 answers
164 views

Single stage MOSFET Amplifier with terrible gain

I'm designing a single stage MOSFET amp for use with a 10k ohm load (R3) and I'm getting abysmal gain. How should I change the values of my biasing resistors?
0 votes
2 answers
57 views

How to improve gain for CC-CE-CC amplifier

I'm trying to design my first amplifier; my configuration is CC-CE-CC. My Vcc is 10V and Ic for 3 transistors are 0.5mA. When i designed this, i wanted the overall gain to be 50 times, ( and around 90%...
1 vote
1 answer
48 views

How best to minimize shoot through with push-pull mosfet driver

I am building a custom made portable chisel sharpener from scratch. (Sick of manual sharpening! Can't find a good one!) The plan is to use an 18v battery as power source, and it will see a lot of use -...
5 votes
2 answers
3k views

Help me understand this high voltage amplifier circuit for driving a piezo actuator

I am researching HV driver amplifiers for controlling piezoactuators. My background is in physics, so I am a bit out of my comfort zone here. I came across the following schematic and have been ...
1 vote
1 answer
1k views

Connect microphone with pre-amp to STM32 ADC

I need to record audio with STM32. I've got electret microphone and pre-amp based on MAX9812. This is a schematic from datasheet: How I can connect this pre-amp to the ADC? If I just connect it as-...
1 vote
2 answers
44 views

Comparator Using Common Gate CMOS

I am currently in the process of designing and testing a CMOS Comparator based of a Common Gate Topology. Below is an extract of the ref circuit I am using: The authors in the paper mention "...
2 votes
2 answers
2k views

How to estimate the voltage gain, Input impedance, current gain, power gain, and output impedance for the amplifier in the fig?

β of the BJT is 100 and from dc analysis it is found that the quiescent point is ICQ=4.12mA and VCE = 6.72V. If the emitter resistor RE is subdivided into RE1=100 Ω and RE2=900 Ω, with bypass ...
0 votes
3 answers
2k views

Amp troubles - noisy TEA2025

Recently I got my hands on a small amplifier board containing two TEA2025 ICs. Not sure what had it been used in previously, but the sound was acceptable, at least when removing some resistors that ...
0 votes
1 answer
55 views

Noise decibel meter - how to convert MAX4466 voltage output to unweighted dB(SPL)

Using this microcontroller with that electret microphone amplifier, I want to build an unweighted dB(SPL) meter as good as it can get - then compare it to this ready made breakout board, this NIOSH ...
0 votes
0 answers
22 views

Single stage CMOS amplifier PSpice design

I'm at the very beginning of my electronics adventure and facing the given problem: I'm trying to design a single-ended CMOS amplifier with small signal gain = 15dB at 10kHz. The load capacitance has ...
0 votes
1 answer
83 views

I have a AD9833 function generator which has the ability to change frequency from 1k to 1MHz but a fixed 0.6V output I want 1V to 10V pk to pk

The frequency changes from the AD9833 DDS chip but it has a 0.6V pk to pk and I need it to be 1V to 10V pk to pk this is my circuit so far the goal is to have an adjustable gain please any adjustments ...
0 votes
3 answers
236 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 ...
0 votes
1 answer
82 views

Why is the real component in my amplifier input impedance negative?

I am designing an amplifier and the input impedance has a real component with a 180° phase shift. From what I understand, resistance can only be positive unless you are designing an oscillator. Here ...
0 votes
1 answer
52 views

Options for line output doubling as headphone output

As the title says, I'd like a combined line/headphone audio output with the following design criteria: ideally driven from 5V single supply (12V available, but noisy) flat frequency response, also in ...
0 votes
2 answers
465 views

How to find collector resistor value in bjt differential amplifier

What value R2 may have in that schema? Anyway it will be loaded by pn-junction of Q5 and will have fixed voltage drop near 0.65V. What value R2 must have if the current source is used instead R1? The ...
0 votes
0 answers
62 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 ...
1 vote
2 answers
31 views

Why does the volume of the preamplifier change when a second audio signal is mixed? [duplicate]

I have two audio signals leading to the amplifier input: the first one comes from the preamplifier, the second one from the audio output of a smartphone/tablet device. Both have a resistor and a ...
1 vote
1 answer
219 views

TPA3110 noise problem

There is noise emanating from each of my two TPA3110 modules(this board & this board.) Even though the noise was not excessively loud, if I put my ear close to the speaker driver, I could still ...
1 vote
1 answer
572 views

How does the overdrive voltage of diode connected load in a common source with a diode connected load limit voltage swing?

I get how the threshold voltage of M2 limits the upper bound for voltage swing, but the book I am reading says the overdrive voltage of M2 also limits the voltage swing. The only reason I can come up ...
0 votes
3 answers
219 views

How to know that the output node of an amplifier is not well-defined?

There are two questions bothering me that may be related. The first is the gain of a simple MOS transistor. I have read that in today's MOS technology, the intrinsic gain of MOS transistors is ...
0 votes
2 answers
31 views

What is the output current of MAX4238ASA+?

I was reading Analog Devices MAX4238ASA+ datasheet, but I didn't find the output current to know which ADC I can put after it. What is the maximum current in normal use?
0 votes
0 answers
48 views

Low noise high voltage gain amplifier

I have a very small voltage output in microvoltage range. I want to amplify it to atleast milivolt. So a voltage gain of 10^4 is required. Can anyone suggest any suitable amplifier for that?
0 votes
1 answer
44 views

LNA operating in saturation

What happens to an LNA noise figure when operated in saturation? I understand that there will be gain and linearity issues, but what about its noise figure? What is the mechanism which will lead to ...
2 votes
0 answers
128 views

Simulation of transimpedance amplifier in LTspice

I am trying to simulate a circuit that is presented in a research paper by Dr Behzad Razavi. I am using LTspice for the simulation (please see the attached image and netlist for the circuit). I am ...
0 votes
0 answers
22 views

Extending load cell wires for weight transmitter connection

I have a load cell that I want to install in a certain location. I plan to connect its output to a load cell transmitter, which is approximately a meter away from the maximum length of the load cell ...
2 votes
1 answer
428 views

Power amplifier simulation and real time experiment mismatch problem

Thanks in advance to anyone who will take the time to read my first post here. At present, I am doing a simulation of a power amplifier in LTSPice. The schematic and relevant files are uploaded in a ...
0 votes
2 answers
483 views

How can I avoid saturation in current source amplifier?

I'm designing a class d amplifier with current feedback as in figure below with the following features: Vbus=50V Iout programmable from 100mA to 1A rms Vout=35Vrms max When the load overcomes the ...
2 votes
1 answer
491 views

PCM1789 DAC direct connection to TPA6138A2 headphone amplifier?

Is it possible to directly connect PCM1789 DAC to TPA6138A2 headphone amplifier? According to datasheet PCM1789 output are differential outputs and the input of TPA6138A2 is also differential inputs. ...

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