41
votes
What is the point of signal amplification if noise is also amplified?
Preamplification is an engineer's cavalry. You put your best forces in the most strategic place so that the infantry can do its job at their skill level.
Low-noise circuitry is expensive and tricky. ...
- 3,613
12
votes
What is the point of signal amplification if noise is also amplified?
In the case of the ADC you should consider the noise the ADC adds.
If it's an ideal 12-bit converter and you are using 0-50mV out of 0-3.3V full scale you effectively have a 6-bit converter (5.95 bits)...
- 384k
11
votes
What is the point of signal amplification if noise is also amplified?
Yes, analog design is kind of a lose-lose. Everything you do to a signal actually makes it worse (even filtering).
The goal is to make it better in the specific ways that your acquisition circuit ...
- 779
8
votes
What is the point of signal amplification if noise is also amplified?
There is a very obvious case where application is very useful: when your signal is going to be transmitted, whether over wires or wirelessly, where noise will be added during the transmission, so ...
- 1,804
6
votes
What is the point of signal amplification if noise is also amplified?
Can you give me a reason to amplify let's say a 0 - 50 mV noisy signal to 0 - 3.3V range by a single ended amplifier which is coupled to a 0 - 3.3V 12-bit ADC?
Sure: resolution.
A 12-bit ADC will ...
- 171k
5
votes
Accepted
Why do amplifiers have minimum frequencies?
Low frequency noise can become fatal to the high frequency noise performance if the low frequency signal is not prevented to be amplified. Low frequency noise can be strong in semiconductors when ...
- 136
5
votes
Why do amplifiers have minimum frequencies?
What would the impact of using a microwave LNA or PA on HF frequencies be?
If it's AC coupled, it has a low frequency cutoff.
Besides that, there's going to be filters and bias networks ; if the ...
- 72k
5
votes
Accepted
Problem with push pull output
Try the complementary Darlington configuration, aka "Sziklai pair" for the output stage, rather than the Darlingtion as shown in the OP. Refer schematic below, just connect the bases of Q3 &...
- 1,683
4
votes
Why am I getting heavy output distortion from a BJT amplifier when driving an 8 ohm load?
start from the load and work your way backwards, all the way to the source.
Agreed, this is the best method.
If you want 1W into 8Ω (for a sinewave) then some basic calculations show you will need ...
- 1,683
3
votes
What is the point of signal amplification if noise is also amplified?
How noisy is your 0-50 mV signal? You didn't say, so I'll use a contrived example with some approximations for a back-of-the envelope analysis.
Case 1 - Apply The Signal+Noise Directly to the ADC
...
- 10.3k
3
votes
What is the point of signal amplification if noise is also amplified?
The point of amplifying analog 50mV signal to 3.3V to read the value with 12-bit MCU ADC is to use the full scale of the 12-bit range of 0..4096.
If you keep the value at 50mV, you have only range of ...
- 137k
3
votes
Problem with push pull output
At that point you may as well put the whole op-amp together :)
The circuit below has +/-1V (2Vpp) input and +/-7V (14Vpp) output. Increase C1 should there be any instability with your particular ...
3
votes
Why do amplifiers have minimum frequencies?
A while ago I played a little with SiGe transistors such as BFG425W and BFP650. I built some cascaded amplifiers and a noise source. The noise generator had about 5 stages of amplification.
I noticed ...
- 2,603
3
votes
Problem with push pull output
Your driver and output transistors have no DC bias.
Since your input signal is a squarewave from the oscillator then you do not need the coupling capacitors.
- 4,288
3
votes
Microwave output power seems inconsistent with supply voltage
There is an impedance-matching network, presumably from a lower impedance at the die itself (which indeed cannot pull drain voltage below 0V), to the characteristic-impedance ports/pins/traces.
...
- 27.4k
2
votes
Why am I getting heavy output distortion from a BJT amplifier when driving an 8 ohm load?
Here's a way that simulates ok, presenting "just enough" input impedance for guitar (really prefer > 500k, but this will be around 200k input impedance, which won't hurt the tone more ...
2
votes
Accepted
A circuit fulfilling equation
I have a simulation of a working 2 op amp design that will provide a function according to the formula you provided.
Simulation Here
Note: you will want a dual rail (+V/GND/-V) power supply for your ...
- 326
2
votes
Accepted
Audio Power Amplifier Layout clarifications
No. Differential impedance is unimportant at audio frequency. Actually this is switching so there will likely be signal at gigher frequencies, maybe 100kHz or so, but still - you don't need to worry ...
- 6,604
2
votes
Audio Power Amplifier Layout clarifications
Audio amplifier does not need characteristic impedance traces. The wavelength is about three orders of magnitude longer than any PCB trace would care about.
Yes, ampacity around an ampere will ...
- 27.4k
2
votes
High voltage high frequency amplifier
Your design does work. And this is how I know:
I designed and build that exact circuit in the mid 1970s. The only difference is that I used capacitors across each resistor in the divider. I sent the ...
- 18.9k
2
votes
Accepted
Closed-loop differential-input JFET amplifier
Think about how this would be done with just an op-amp, you have the differential inputs and an output and when you want to close the loop you connect the output to one of the inputs through a network ...
- 19.6k
1
vote
High voltage high frequency amplifier
No, that's not possible. Large MOSFET gate capacitances, and of that a stack of four on each side, will severely, and intentionally, limit your bandwidth.
You need to design a simpler circuit. It's ...
- 90.6k
1
vote
Accepted
Do we need to guard the input traces of an audio power amplifier?
Do we need to provide guarding for +IN and -IN on the PCB layout?
No, if you were worried about high frequency getting into the input terminals then it would be better to place a high frequency cap ...
- 78k
1
vote
What is the point of signal amplification if noise is also amplified?
There are many reasons to amplify a signal even if the S/N ratio becomes worse afterwards. For example, if your signal is a square wave 0-50mV and you want to drive a TTL circuit you need to amplify ...
- 111
1
vote
Accepted
Dropping the line voltage on an HH Scott 265A tube amplifier
Someone linked you over on Audio Karma. I am uploading what I have for Scott 265a bucking transformer
- 26
1
vote
How can I calculate the gain of this high pass active filter?
I can see two cascade-connected AC-coupled single-supply inverting amplifiers built with a single LM358 which contains two op amps.
An op amp with dual supply (e.g. ±5V) is expected to amplify ...
- 30.3k
1
vote
How can I amplify an analog DC voltage signal?
Subtract 0.6V and scale by 9 and add 1V.
Or in math terms:
VOut = (VIn - 0.6V)x9 + 1V-> Vout [1;10]V with Vin [0,6;1,6]V
Or in circuit terms:
simulate this circuit – Schematic created using ...
- 3,141
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