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)
Questions tagged [gain]
656 questions
34
votes
5 answers
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 but why would some one use specific value. i.e Rf…
dr3patel
- 1,620
- 3
- 22
- 31
29
votes
6 answers
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 similar question here but it did not ask for nor…
scanny
- 7,062
- 5
- 47
- 87
15
votes
6 answers
Why do (microphone) preamp designs tend to limit opamp gain to max 60 dB?
Looking at many pro recording quality microphone preamps, I noticed that every design I looked at that uses an opamp (discrete or IC) limits the gain provided by the opamp to about max 60dB. While most preamps use another stage (transformer(s) or…
MeatBallRagu
- 185
- 1
- 7
14
votes
4 answers
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.wikipedia.org/wiki/Gain#Voltage_gain
Here, I understand…
Naetmul
- 265
- 1
- 3
- 8
13
votes
7 answers
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 gain of 2 like so. Can I modify it to have a gain of…
codedude
- 562
- 4
- 8
- 19
13
votes
5 answers
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 to
change the gain, when required from a micro…
Robin
- 327
- 2
- 9
11
votes
1 answer
Why is my instrumentation amplifier's gain non-linear?
I am using an AD8226 instrumentation amplifier as the pre-amp in a circuit which uses a micro fuel cell oxygen sensor to measure oxygen content in a gas stream. The pre-amp is configured in single ended supply mode, with a 5 V supply. Gain…
Matt B
- 165
- 2
- 12
11
votes
3 answers
Common Emitter not amplifying
I am trying to make a 27 MHz carrier wave transmitter from a crystal oscillator and a secondary amplifier. This is the complete circuit:
simulate this circuit – Schematic created using CircuitLab
The first part, left of C6 is a colpitts crystal…
Golaž
- 1,967
- 3
- 33
- 51
9
votes
4 answers
Why is open loop gain important in an op amp?
Can someone tell me why open loop gain in an op-amp is important?
Why should someone measure or even care about the open loop gain when op-amps are always used in closed loop with feedback only?
Freshman
- 655
- 7
- 19
8
votes
1 answer
Is the beta of a BJT really the same as h_FE?
I am currently re-reading my old textbook Microelectronics by Millman and Grabel. Attached two pages. Here is a somewhat theoretical question on large signal parameters for the BJT.
Starting with Ebers-Moll equations (3-6) and (3-7) and assuming…
Dr H.
- 81
- 2
8
votes
2 answers
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 I had to find was defined as: $$G_v=\frac…
uriyabsc
- 493
- 3
- 13
8
votes
3 answers
Opamp stability given in not inverting configuration
If a datasheet (like AD828) says that an opamp is stable at Gain >2 (or reccomends to work with G>2, hence it is clearly not unity gain stable), what can we deduct about its stability in the inverting configuration at G=-1; G=-2 or G<<-2 (like in…
Gianluca G
- 401
- 2
- 10
7
votes
4 answers
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 that it is to avoid the negative feedback by the…
Alex
- 1,018
- 2
- 12
- 26
6
votes
2 answers
How is the gain/phase vs frequency measured for opamps?
Opamp manufacturers post graphs like these in datasheets:
How is the data for this graph measured? Is it calculated using the mathematical model of an opamp?
miceuz
- 5,523
- 3
- 39
- 49
6
votes
2 answers
PGA207 op-amp gain issue
I have an issue with the PGA207 instrumentation op-amp.
I connected it as a voltage buffer, as seen in the following image:
When I connect a 1 kHz, 2Vpp sine wave to the non-inverting input (pin 5) and measure the output on pin 11, the signal…
Adriaan Sadie
- 77
- 4