Questions tagged [gain]

Simply the ratio of output signal to input signal, this dimensionless quantity is a measure of the amplification of a signal which may be represented by voltage, current of may even have a digital representation. A very general concept sometimes used to describe attenuation (when gain < 1)

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46 views

OP-Amp virtual gnd to real gnd gain control

Can someone please explain why a potentiometer from op-amp virtual ground to real ground control the gain?
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How can we find the voltage gain of a BJT circuit if the Vin and Vout are on different transistors?

I am trying to find the voltage gain of the circuit below. I drew the small-signal model for it (shown below). I know the formula for finding the voltage gain of a common-emitter BJT with and without ...
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Can I multiply the magnitude of two cascaded amplifiers?

I'm trying to derive an expression for the magnitude of \$ \frac{V_{out}}{V_{in}} \$ for this circuit from Razavi. I know that \$ \frac{V_{out}}{V_{in}} = \frac{V_{out}}{V_{X}} * \frac{V_{X}}{V_{in}} \...
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70 views

Problem with op amp output hitting bottom rail on output stage for DIY 3D printed strain gauge. High gain is needed

So the goal is to take our differential input from our experimental full bridge strain gauge and amplify the signal to a gain of roughly 5500. The output signal would then be going into a 12-bit ADC ...
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3answers
85 views

single supply op amp non inverting level shifter for NTSC signal processing from 0-0.7Vpp to 2-2.5Vpp

I am performing an RGB modding of an NTSC CRT TV. By performing tests I found out that the chroma chip will accept 2-2.5V Vpp RGB signal to get the proper colors. So I need to amplify and shift my ...
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1answer
54 views

What is the output of a cascaded amplifier?

I wanted to make an comparator with cascade of amplifiers of equal gain, output impedance etc. We know that we can approximate it as single pole system , thus a resistor and a capacitor in the output ...
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1answer
111 views

Audio Amplifier With MOSFET

I am working on a new project that seeks to implement a three-stage audio amplifier. One of my stages consists of a CASCODE circuit using the BF998 NMOS transistor. For this stage I am struggling to ...
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47 views

Maximum Current Gain Possible for a 100 mA PNP transistor

I have a pulse charging circuit where the maximum current is limited by the hFE of the PNP transistor (DTA144EE). The typical hFE at room temperature is ~220 as shown in the plot below. There is of ...
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85 views

What is the physical significance of beta and alpha in BJT?

I have read in the book that beta is the ratio of collector current to the base current in common emitter configuration and alpha is the ratio of collector current to emitter current to common base ...
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61 views

How to increase the voltage gain in a Class AB Transistor

I have the following circuit design of a Class AB Amplifier which amplifies the input voltage with a voltage gain of around 42. However, I'm wanting to increase that gain to around 80. Does anyone ...
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Why use gains on an ADC

Why do some people use some sort of gain either external amps or the one built in to the ADC itself and not just do the calculation in software. I do not think its that expensive of a processing power ...
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LM13700 Gain Calculation

I pulled some LM13700 OTAs from an old board and tested them. All voltages, currents, and resistances were measured. I had the expected (approximate) voltage gain using the equation \$ A=(R_2/(R_1+R_2 ...
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Two lock in amplifiers, almost identical setup, different AC Gain?

I am measuring a voltage output of around ~110 uV for two thermometers. Other than the placement of the thermometers on the sample and the frequency of the lock ins (7225 DSP at 11.137 Hz, 13.373 Hz), ...
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401 views

Is a resistor trimmer a good idea for adjusting the gain of an op amp circuit?

I'm designing this circuit to measure temperature with PT100. R10 must be calibrated to obtain the desired gain. I have thought of using a resistor trimmer to adjust the gain similar to the following:...
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1answer
43 views

AMC1200BDUBR Gain is 4 instead of 8

I want to measure grid voltage with AMC1200b. I used a resistor voltage divider and I lowered grid voltage from 110v(rms) to 110mv(rms). I fed the 110mv(rms) signal to AMC1200b (for the first side of ...
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Is there a programmable variable resistor

I have a current signal that can vary in amplitude. I currently have a transresistance amplifier which uses 330 Ohm resistors. However the amplitude of this signal can vary and I would like to be able ...
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82 views

Voltage gain from AC

Voltage gain CE & CC from AC Can you tell me please if I am true in calculation of gain of this circuit? Assumption: gm is known and beta=inf, Early VA=inf => gbe=0, gce=0. Here the Matlab code : <...
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52 views

Constancy of gain bandwidth product for amplifiers

I've seen the assumption of gain-bandwidth product being constant for some amplifiers. More specifically for a compensated op-amp. Is there any mathematical proof to establish why the product is ...
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51 views

Voltage gain from the Amplifier input to the load

I don't understand where the solution for part C coming from. What I thought is also Vo/Vi. I found Vo as 303 mV and Vi as Vs*(10/10+100). However in solution it seems my thought is wrong. How should ...
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613 views

Do we always take the corner frequency of a filter at exactly -3dB?

I'm doing some work on filters, but all the references I can find use a 'perfect' gain characteristic, with the trace starting at 0dB. Is the measurement for corner/cutoff frequency always taken at ...
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4answers
497 views

How are the -3dB point and the pole of an op-amp related?

I have been looking at AC frequency responses for op-amps and I was wondering how an op-amp's pole and the frequency at the -3dB point are the same? They both mark the location where the gain starts ...
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76 views

Two stage amplifier, low gain at high frequencies

When I simulate one stage amplifier it is capable of amplifying to a much higher frequency than a two stage amplifier. I added a 100 ohm resistor to reduce the gain of the two stage amplifier so both ...
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1answer
59 views

How to make sense of the math behind differential opamp

My first question here! So, I'm designing a simple fully differential amplifier. The final target will be to implement a low pass filter (but I'm not there yet). Although all seems perfectly fine in ...
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1answer
38 views

How can I find the slope at Vout/Vin at Vin = 0, from the datasheet about Op-amp?

I'm trying OpenModelica and I'm going to simulate an Op-amp. (No it's not Windows 95, it's IceWM + Ubuntu 20.04) But I wonder where I can find the slope Vout/Vin when Vin = 0 in the datahseet? I have ...
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Power gain values at the microwave amplifier

I have generated graphs in AWR software for signal gains, G_A, G_max, G_P and G_T, respectively. The amplifier I am using is "HMC141". Unfortunately, the values that came out look like this: ...
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150 views

Inverting opamp amplifier

The gain of an ideal opamp is considered infinite and Vout=K(V+ - V-). where V+ is the non-inverting input and V- is the inverting input. The output voltage in the case of an inverting opamp amplifier ...
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124 views

Don't understand this zero pole plot example

I'm reading a book (see figure 5-12) about (among other things) pole zero plots and there is an example I don't understand. For the schematics and formula below: it adds the following zero pole plots:...
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1answer
146 views

How to get the DC gain of an active high pass filter?

Edit: I think maybe I am confusing terms (it has been a few years since my last electronics class). I am trying to get the expression for the gain of this active filter amplifier circuit in terms of ...
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61 views

Miller effect adjustment

I'm confused about the following discussion of the Miller effect/approximation from Razavi (image below). I don't understand the premise of the question. If one reasons that the gain seen by the ...
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1answer
53 views

How is the Tx/Rx Gain calculated in USRP?

I'm using Software Defined Radio NI USRP 2922 (Universal Software Radio Peripheral). I know that USRPs are uncalibrated devices. In many exampls you can set the so called Tx or Rx gain (as in the ...
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1answer
42 views

Why does adding a gain to a Sallen-key second order HPF change the amplitude response?

As the title suggests, I have done all the necessary calculations to implement a gain into my second order stage of my 6th order high pass filter but for some odd reason, it would change the amplitude ...
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2answers
130 views

How do I find the -3dB point on a given graph

I just performed an AC Simulation on QUCS and was asked to find values of gain and phase at low freq. and high freq and at the -3dB frequency point with the roll-off slope. The circuit is an RC ...
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3answers
710 views

In an amplifier, does the gain knob boost or attenuate the input signal?

I'm thinking specifically about guitar amplifiers, but I'm guessing this applies to all audio amplifiers. I understand the practical function of a gain knob, but what's not clear to me is whether the ...
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1answer
33 views

hFE value (a.k.a β or gain factor) for transistor, at different voltage

I've been looking into the BC337 NPN transistor, and I saw in the hFE graph on page 3 of the datasheet, that the graph was at 1V from the collector to emitter. Is there any way to find out the hFE ...
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1answer
60 views

What causes the Inverting input of this op amp to conduct current?

When I analyse this circuit to understand it's working, I got stuck at one point. Have a look on this circuit. When the feedback resistor value is 2.2k as shown in fig, I got the expected output with ...
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1answer
48 views

Amplifier circuit for Bently Nevada velomitor 330525

I'm in need of measuring vibrations and I have access to these Bently Nevada velomitors. I'm not sure how to design a ampliefier circuit for the signal. The datasheet is says that it is a piezo ...
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2answers
124 views

Recreate “Voltage gain vs Frequency” graph of Op-Amp in LT Spice

I am trying to recreate the "Voltage gain vs Frequency" graph of the LT1037 Op-Amp in LT Spice. According to the datasheet page 6 the graph looks like this: - Trying to recreate this in LT ...
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Open Loop Gain in Buck Converter

I'm trying to understand this application note from On-Semiconductor regarding the loop control design of buck converter Designing Stable Control Loops for High Current Voltage Mode Synchronous Buck ...
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39 views

How does the thickness of a dipole antenna affect the gain and the field strength?

I was asked this question on an exam and I couldn't answer it. I've searched the web and looked in my books but I can't find any information about gain and field strength vs. dipole thickness. I know ...
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83 views

transistor amplifier

My teacher asked me to design an amplifier circuit using BJT transistors with following properties: (Is=10fA , beta=100, Vce sat =0.2) I can use as many transistors as i want but i try to minimize the ...
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87 views

how to find Vout/Vin in this circuit? BJT frequency response

I have been struggling for 1 hour trying to relate Vout to Vin. However, I truly cannot. I tried KVL, node analysis etc everything that I could. Can you help me pls? The topic is frequency response of ...
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3answers
423 views

Why is there a resistor in the feedback section of this buffer circuit?

When I searched for op amp buffer circuits on internet, I found this picture. I just want to use it as a buffer circuit. So, obviously the gain of this configuration will be 1. I would like to put 0 Ω ...
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1answer
61 views

Identifying transistors

I have found an old driver board (probably the mid 80's) for stepper motors (rated at 1.25V 3.8A) and I want to rebuild the H-Bridge using the parts on the board and a micro-controller as an input. I ...
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2answers
204 views

Is there an easier alternative for finding the gain of this operational amplifier?

My question is: Is there an easier method than what I've tried, that I can use in order to find the parametric gain in the following circuit? If so, what is it? The circuit: Where the parametric gain ...
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42 views

Small signal gain

I'm struggling to find the small signal gain of the circuit shown below. I am trying to find the gain from Vout to Va. Note that Vout corresponds to the output of an amplifier. Any help is much ...
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1answer
138 views

Reducing noise in microphone amplifier circuit at higher gains

I am using the below circuit to amplify the signal from an electret condenser microphone for analysis by a microcontroller to detect short bursts of sound. The circuit runs off a ~4.5V supply from 3 ...
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1answer
43 views

How gain is changed in this Op-AMP integrator?

Hi, I am simulating this circuit for personal development. The gain of the integrator can be calculated using the following formula: Gain = -Rf/R1 (1/(1+(2 x pi x f x C1 x Rf))) But, how to calculate ...
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1answer
49 views

Formula to calculate the isotropic range of a signal

I am wondering, is there a formula to calculate the range of a signal with a given frequency and output power? For example, how do i find the range of a 580khz AM signal on entirely flat terrain with ...
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1answer
138 views

Audio equalizer circuit using multiple feedback bandpass filter for each frequency band

I have a project to design an audio equalizer circuit with the following specifications. Bass band, center frequency = 180 hz, quality factor =0.7, range of adjustable gain 0.4-8 Midrange band, ...
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2answers
64 views

Is it possible to add gain to a dipole antenna without changing its radiation pattern?

In every reference book I've seen, an electric dipole antenna has basically a donut pattern, and as things are added to increase the gain (directors, reflectors etc) the pattern changes. I've always ...

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