Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [power-amplifier]

An electronic amplifier that amplifies a low-power signal in order to make it more suitable for an application that requires higher power (e.g. driving a speaker). Power amplifiers have special challenges compared to lower power amplifiers (e.g. a voltage amplifier, which amplifies a signal's voltage but does not provide much output current capability); such challenges include more board space, cooling components that are dissipating high power, etc.

An electronic amplifier that amplifies a low-power signal in order to make it more suitable for an application that requires higher power (e.g. driving a speaker). Power amplifiers have special challenges compared to lower power amplifiers (e.g. a voltage amplifier, which amplifies a signal's voltage but does not provide much output current capability); such challenges include more board space, cooling components that are dissipating high power, etc.

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How can LM386 follow a signal when it becomes negative?

Here is a picture from the datasheet of the LM386. Obviously, the input signal is swinging above and below the ground, but pin 4 is not connected to a negative supply. It is connected to the ground (while pin 6 is the positive supply.) How can this…
MikeTeX
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What specifically causes damage when a transformer-coupled valve amplifier has no load across the secondary coil?

I'm new to this forum, so be gentle! I'm an electronics and computer systems engineering student, and I always thoroughly enjoy audio circuits, especially examining older valve based designs (I play guitar, who would've guessed!). My degree is very…
AL270
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Confusion between Class B and Class AB Amplifier

I am reading about output stages of an amplifier and classes of amplifier. The following circuit is named as "Class B" amplifier. From my understanding, the above circuit should be a class AB amplifier. Because we have a constant biasing, so both…
sundar
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Linearity of power amplifiers

How are power amplifiers linear? Although they have some distortion they are still considered linear. I tried referencing many materials, but I couldn't find an answer. The characteristics of transistors are non-linear for large signals and hence…
dwight
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Why is it preferable to use NPN transistors for both high-current-output devices in a push-pull amplifier?

With reference to the below circuit why is it preferable to use NPN Silicon transistors for both high-current-output devices in a push-pull amplifier?
Andrew Davis
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BJT base connected to ground and still operates?

When in university I used to get confused how a transistor (NPN) can draw current from ground. I'm now studying power amplifiers and again, this same configuration appears. How does Ir draw current from seemingly nothing/ground?
user160063
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How to design wide band amplifiers?

I've been designing microwave power amplifiers and LNAs for school, I design in microstrip and my matching networks usually consist of stub/line sections or similar arrangements, I have also designed more sophisticated networks for wider bandwidths,…
S.s.
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Why is it possible to have undistorted power amplifiers?

In Albert Malvino's book "Electronic Principles," he says there is a 10 percent rule for small signal amplifiers wherein the AC signal current must be less than 10 percent of the emitter current so that the resulting amplified signal is not…
hontou_
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What is the purpose of diodes after RF power amplifier and before LPF?

I am planning to build an RF transmitter using an integrated PA module (RA30H1317M1). While studying schematics of similar transceivers, for example IC-2200H (that also has a PA module) I see all typical transmit chain components like the PA,…
filo
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In a Class-C power amplifier, what does the resistor in the base do?

Look at the picture, which shows a Class C power amplifier (source). What is the role of the resistance in the base of the transistor, and what happens if it's removed?
Alex L
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DC on op-amp input, audio amplifier

I have built the following audio amplifier circuit on a breadboard. The circuit works. However the circuit makes a DC offset on the non-inverting input of the op-amp. simulate this circuit – Schematic created using CircuitLab I get the input from a…
keffe
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Benefits of a differential PA in an RF power combiner design

Looking at the schematic for the Shure PA770 Antenna Combiner (found in their FCC listing) we can see the design is fairly straightforward, some amplification before combining via a typical Wilkinson divider. What isn't immediately obvious to me is…
jduncanator
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Transistor bias goes negative under input

I am trying to make a simple class A audio amplifier with one transistor (TIP41, NPN) in common emitter configuration as shown in the pictures. The problem I have is that when I add the input signal (more than 1 V), the transistor's base bias…
Alin Paladin
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Can the DC offset on a line input trigger power amplifier shutdown?

I am looking at a Kenwood HiFi receiver (KR V5090) from the late 90s that sometimes loses sound on one channel. Granted, it can just be replaced, but I always like to give devices a second chance by attempting to repair them. With this Kenwood I've…
E. van Putten
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DC stability issue with this audio amplifier

This design has a stability issue. The DC output point (without input signal) should be 0 V with a small offset, but it's not the case, because this point is not stable. Initially the amplifier had an offset of about 200 mV but it wasn't stable; it…
mtx4
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