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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20 views

Is it possible to implement a high-side current mirror with only NMOS FETs?

I need to implement a difference amplifier only using NMOS technology. I am struggling when trying to reference the voltage difference to ground. From my reading it looks like I need a high-side ...
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44 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 ...
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33 views

Opamp Current Sink + FET circuit help

I've been trying to figure out a design someone made for controlling a precision high current LED, and it's got me in a bit of a pickle. For the life of me, I can't figure out this exact op amp ...
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20 views

Signal lines from transducer made common by op-amp

I am trying to amplify the difference between signal lines off of a Wheatstone bridge based force transducer. I've wired up an LM358N Op-Amp as shown below in a differential amplifier. With R1=R2=...
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71 views

Audio amplifier instability inexplicable [closed]

here is the problem, I've designed a power amplifier of which I cannot post the schematic for security reasons, I hope you can help me the same by describing the problem. It is an analog amplifier in ...
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26 views

Skype, windows 10, recorded videos, speakers [migrated]

I'm using the above and those who listen in on Skype are having problems hearing certain recorded videos. They can hear everything said on microphones at our location but when a video or music on ...
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45 views

How to start designing a multistage amplifier? [on hold]

My professor will make us do a project and it's to build a multistage amplifier with these specifications: Design a three-stage amplifier with Bipolar and CMOS transistors to satisfy the ...
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1answer
67 views

OpAmp resistor to ground in feedback loop

I am currently tasked with improving the design of an electrometer unit. It was NOT designed by an electrical, and there are some questionable design practices. My question is concerning the first ...
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28 views

Common Collector Amplifier - Explanation?

I am new into electronics, and I dont get it how we find input and output impedance of Common-Collector Amplifier. I mean, I dont know what we are looking at when we are trying to find input and ...
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28 views

Finding transfer function of an amplifier

I would like to know if the transfer function i found is correct : TF = Vs/Vi = -(R-Rg)/(R+Rg) In my case Rf = R1 = R2 = R ( i just did not find the right schematics ) And V1 connected to V2 and ...
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20 views

NMOS common source amplifier outputl resitance and bandwidth [closed]

Considering this circuit, how can I calculate the bandwidth of the amplifier?Also, what is the output resistance Ro?
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30 views

bandpass filter design help

I need help designing a band pass filter that passes frequencies only between 500 and 1000Hz Attached is my filter that i made in multi-sim but for some reason nothing comes up on the oscilloscope. ...
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37 views

How does a high pass filter and a low pass filter work for an amp?

I'm researching how to incorporate treble and bass into an amp. X1 is for bass, X2 is for treble and X3 is for volume. Intuitively, for me, if a high pass filter only allows frequency above a ...
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1answer
72 views

500 mW RF amplifier for 170 MHz design

For a new project I need to build an RF amplifier for continuous-wave with about 500 mW (27dBm) output at 170 MHz. It doesn't need to transport data, it is only for measuring purpose. The input ...
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2answers
78 views

Fixing the Collector Current for a BJT amplifier

I am doing a design of a BJT amplifier with the voltage divider biasing. I am trying to set up my Q points in the DC analysis. Based on my notes from school and research online, I have set up the ...
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35 views

Difference between RS PRO 846-171 and INA125P for strain gauge amplification?

I am implementing a solution to read several strain gauges at once. Since I am using RS as my provider, I was about to buy the RS PRO 846-171 chip which is an amplifier specifically designed for ...
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3answers
60 views

Gain-Bandwidth Confusion

Hi, I saw this online and I'm a bit confused why they chose B as the correct answer. My answer was: The DC voltage gain is 20dB, so -3dB frequency will occur at 17dB gain. 17dB in normal gain is 7....
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What gain can one expect from a single stage cascode amplifier biased with a cascode current source (45 nm CMOS technology)?

Is a gain of 135 good enough for a single cascode gain stage? Let's say I wanna put it within a larger CMOS operational amplifier later on. I am using 45 nm CMOS technology. Edit: I've included the ...
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1answer
48 views

Why is output voltage of current-to-voltage amplifier the same when input resistance is larger [closed]

Whenever we increase the resistance (imagine putting a bigger resistor in front of an amplifier) going into a current-to-voltage amplifier, why does the output voltage of that amplifier stay the same. ...
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2answers
83 views

How to amplify a 0-5V PWM Signal to 0-12V, 10A

I need a Power amplifier which amplifies a 0-5V Arduino-generated PWM Signal to a 0-12V Signal with 120W, for powering a ZVS induction heater. Linearity is not important because i can correct the ...
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1answer
73 views

Need help level shifting

I have an AC signal (500 - 1000Hz) 1v peak to peak that sweeps around 0v. The signal needs to be shifted to 0.5 -2V, a gain of 1.5... The power supply is +-10V. Just looking for someone to point me in ...
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59 views

how to increase output power of multistage audio amplifer?

In the circuit given below, I'm working on an audio amplifer. It is driving a 4-Ohm load (speaker.) Input : 1.1V peak-peak sine wave of frequency 1Khz. Input dc = 12v Output : 4-Ohm load. Gain = (8 ...
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44 views

Modifying the volume pot in a stereo amplifier

This must be a rather basic question. I have stereo amplifier with a 30K potentiometer serving as a volume control pot (two of them ganged together, to be precise). The pot is connected as a classic ...
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1answer
85 views

Long-tailed pair - gain and bandwidth

I'm trying to understand this schematic of this differential probe: I marked some blocks. I have some questions about the block I marked "Long-tailed pair" (LTP). I have no experience with LTPs so ...
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2answers
249 views

Please review this electric guitar buffer / volume / tone circuit

I have been tinkering with creating a MOSFET buffer circuit for my guitar to boost the high impedance output from the pickups to help drive the signal through long cables and pedal boards. This also ...
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3answers
76 views

AC to DC rails sag excessively when loaded

I'm just experimenting with rectifying a 120v to 12v dual winding transformer and smoothing it out two a dual rail power supply while I work towards attempting to build a clean power supply. I ...
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3answers
126 views

BJT Low Current Consumption Amplifier

I'm trying to amplify a 20mV ptp signal to something around 1V ptp. I intent on only doing this in one stage and require the amplifier to be very low power consumption (3.3V supply max 1mA for entire ...
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2answers
101 views

Maximum Symmetrical Swing for BJT Amplifier

I am doing the DC analysis for a BJT amplifier using the 2N3904 transistor in a common emitter configuration. I am given +Vcc = 18V and need to find Rc to give maximum symmetrical swing. From my ...
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1answer
88 views

Audio amplifier with strange open loop, is it an oscillator?

straight to the problem. Here is a picture of frequency response of my amplifier in the simulator (LTspice or Pspice both give same results). Normally, in the open loop i see a phase of 90° which ...
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1answer
34 views

Transimpedance Amplifier for Photodiode with low Shunt-Resistance

I am designing a transimpedance amplifier to amplify the signal of a photodiode. I plan to use the IC ADA4350 (datasheet), it contains an Op-Amp and analog switches to select different feedback paths ...
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2answers
62 views

Emitter Follower as a Current Amplifier

Reviewing Basic amplifier stage properties, I found unanimously that a Current Amplifier has a Very Low (ideally zero) Input Impedance and a Very High (ideally infinite) Output Impedance. The Emitter ...
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1answer
33 views

Cutoff frequency of class A common-emitter amplifier

I'm trying to understand the operation of a class A common-emitter amplifier, but I'm struggling to understand how the equivalent resistance for the cutoff frequency of C1 is determined. I also can't ...
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1answer
33 views

How to get the gain for this MOSFET amplifier?

This is a common drain MOSFET amplifier: simulate this circuit – Schematic created using CircuitLab This is its small signal model at low frequency: simulate this circuit I am at a loss as ...
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39 views

Need help with level shifting and amplifying a signal

I have a 1V pk to pk analogue signal and need to shift and amplify the voltage to 0.5-2V.The supply into the amplifier is ±10V. The frequency of the signal is 500 - 1000Hz. What sort of circuit ...
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1answer
20 views

Finding voltage gain and current gain using the load line in a common emmitor transistor amplifier

So this question is really annoying me for a while so I needed some help. I am given the output characteristics curve for a CE transistor amplifier. I also managed to draw the load line. They have ...
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1answer
34 views

How to obtain a high precision mV signal within a specific interval using a variable resistor?

I want to design a circuit which outputs a signal ranging from 0-70 mV using a variable resistor ranging from 80.51 Ohm - 183.05 Ohm and a supply voltage of 12 V. My idea so far has been to make a ...
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36 views

Sony Home Theatre Reciever producing high frequency constant volume noise while powered on

Equipment: Sony Digital Audio Control Center (Digital Cinema Sound) Model No: STR-KG700 Problem: High Pitch Buzzing coming from speaker output and headphone output (when plugged in). I have tried: ...
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2answers
77 views

Op - Amp: Linearity, Negative Feedback and Virtual Short

I need some explanations about Linearity, Negative Feedback and Virtual Short for an ideal Operational Amplifier. Precisely, I have been always told that an operational amplifier with negative ...
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1answer
86 views

Choosing Collector Current for Transistor Amplifer

I see in the guides to standard Bipolar Transistor circuits (emitter-follower, common emitter amplifier), they always say: Choose a quiescent current of 1mA. How is this value chosen? I look at the ...
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3answers
55 views

amplify/increase current from 9v battery

I have a working circuit that generates a signal (a range of slow and fast tones) and sends them to a speaker. I tried to switch to a piezo driver and speaker and was successful using the MAX9788 as ...
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1answer
57 views

Why noise when increasing amplification of last cascade of transistor amplifier?

I've made small amplifier for hand-made electric guitar - it is just two transistor cascades - and I've found one curious effect when increasing amplification. Some annoying noise (just typical ...
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2answers
1k views

Building an amplifier out of diodes

It is quite obvious that we can't build an amplifier out of resistors (because of their linearity). But is there a circuit theorem that states the impossibility of building an amplifier out of diodes (...
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2answers
78 views

Non-inverting amplifier with variable gain from 1 to 15

I need to design a non-inverting amplifier with gain from 1 (unity) to 15. From what I read, in theory this can be achieved by using a pot as the feedback resistor, but in practice this will only work ...
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2answers
49 views

Hand contacting op amp photodiode circuit causes interference - what ist the physic behind it?

I am new to analogue electronics and I am still learning about op-amps. I use the most common circuit for amplifying a photodiode's signal to measure it with an ADC: Amplification gain is 1M, the ...
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1answer
91 views

How can I get/build a current controller/amplifier?

Background: I have a Lorenz-actuator (coil+magnet) that I need to control precisely using a computer. The computer signal is output from a dSpace microLab box as an analog ±10V signal. This signal ...
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2answers
33 views

Question regarding Transresistance Amplifier Circuit

Something that makes me confused while reading a tutorial on the Transresistance amplifier circuit. Here is the picture of the circuit. It basically measures the current across the photo device and ...
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1answer
43 views

Microphone Pre Amp Book? [closed]

I'm wondering if there's a book that discusses resistors, capacitors, inductors, transistors, transformers, impedance, op amps, power supplies, and the general circuitry of a microphone pre amp. Thank ...
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16 views

Prevent click/pop from transient when bluetooth receiver disconnects?

I have a Logitech bluetooth receiver connected to my hifi to allow kids etc to play music from iPhones/ipads. However, it seems that the receiver itself has a sleep mode when no signal is being sent,...
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1answer
38 views

Speakers Power and Quality Difference Factor

I started tinkering with speakers (mostly amplifier circuits) and I learned a lot about how sound and amplifying works but I don't understand how to increase quality I have several kind of speakers , ...
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1answer
60 views

How to get stereo and mono signals simultaneously?

I have PAM8403 circuit module to drive my two 3W speakers. I want to drive a subwoofer with a different amplifier. I have a 3 inch subwoofer, and I'll get an amplifier for that. My question is how do ...