# 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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### Dependence of transistor current gain on operating conditions

According to "Gray & Meyer: Analysis and Design of Analog integrated circuits" transistor current gain Beta (in forward-active region) depend on operating conditions of the transistor. Region 1 ...
4answers
10k views

### What is the bypass capacitor at the emitter of a common-emitter amplifier for?

Why do we have the by pass capacitor parallel to R(E) in this amplifier circuit? They say it is to bypasses the RE resistor for AC signals but then why is it required to by pass the R(E) They say ...
5answers
65k views

### Choosing resistor values for inverting amplifier and why?

The gain here is A = -Rf/Rin. However, lets say I want a gain of 10 V/V. Which resistor value would you choose and why? I know that you could have infinite number of combinations for these resistors ...
4answers
14k views

### Confusion between Voltage gain & Voltage gain in decibels (dB)

The definition of voltage gain is $V_{\text{out}}/V_{\text{in}}$. However, I read some articles about the gain in decibels, and I have a confusion now. Here is an article about it: https://en....
7answers
9k views

### Switching op-amp gain resistances - how?

Given the following circuit: What is the component / circuit I should be using to switch the signal between each of the gain resistors? (the ⊠s in the schematic) The inputs ID0 to ID2 are TTL (...
1answer
613 views

### BJT Differential Amplifier Common Mode & Differential Mode Gain

I have a few questions about how to derive the differential gain and common mode gains: simulate this circuit – Schematic created using CircuitLab Differential Gain: Taken from Art of ...
3answers
4k views

### Why is an op amp's bandwidth higher at lower gains?

If I build a resistor network where the op amp has a lower gain, it is able to maintain its gain for a larger bandwidth. Why?
3answers
253 views

### Cascaded BJT Amplifier Load

In my first layout, with a 9.2k load I get a gain of ~55 (20mVpp in -> ~ 1.1Vpp out). My current understand is that if I replace the resistor load with something else that presents as 9.2k (i.e. ...
6answers
9k views

### What is noise gain, really? And how is it determined in the general case?

UPDATE: This question triggered what might fairly be called a research obsession for me. I've gotten pretty close to the bottom of it I think, I've posted my findings as an answer below. There was a ...
4answers
907 views

### What is the closed-loop gain in this op amp circuit?

For the op amp below Open-loop gain is $A=2\times10^5$ Input resistance is $R_i=2\,M\Omega$ Output resistance is $R_o=50\,\Omega$ I am asked to calculate the close-loop gain $Vo/Vs$ and ...
3answers
3k views

### Can someone explain this gain & offset op-amp circuit?

I'm having trouble understanding the circuit in the photo below. I know that it's a gain and offset amp designed to convert 0-2.5 V range to +/-10 V range (hence it has a gain of 8 and an offset of -...
3answers
43k views

### Op Amp gain less than 1?

How would I design an op amp with a gain of less than 1? Is this even possible? Also would it matter if I used a non inverting or an inverting op amp? I've designed a non-inverting op amp with a ...
4answers
295 views

### Gain of an active filter without calculating the transfer function with two OP-AMPs

I need to calculate the gain of the filter without explicitly calculating the transfer function, ie I have to replace the capacitors with an open circuit. The problem is that I've been trying to solve ...
1answer
3k views

### Gain-bandwidth product proof for open loop/closed loop opamp

On the forum, post #12, Ghar claimed that the proof gain-bandwidth product from wikipedia is awful and he gave another proof but with feedback. https://en.wikipedia.org/wiki/Gain%E2%80%...
2answers
13k views

### What potentiometer should I choose?

I want to create a sound amplifier with the LM386 and I need a potentiometer. I don't have a clue what I'm doing (:P) but I've printed out the datasheet (for the LM386) and had a look at it. So I ...
2answers
965 views

1answer
7k views

### Determining DC gain of single supply op-amp (no AC component)

I'm building a homebrew PIC programmer, and want to support devices with varying Vpp voltages, so I'm using the DAC output of a PIC16F1825. But the PIC is supplied with a +5V Vdd, so that's the ...
1answer
101 views

### Gain of an active filter without calculating the transfer function with two OP-AMP's [duplicate]

I need to calculate the gain of the filter without explicitly calculating the transfer function, ie I have to replace the capacitors with an open circuit. The problem is that I've been trying to solve ...
1answer
4k views

### Bypass source capacitor JFET

I know there were some changes applied to voltage amplification formula of BJT when "Ce" (emitter bypass capacitor) was connected to the circuit. How is it with JFET (MOSFET too) and its bypass ...