voltage and current amplifier

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bhuvaneshnick

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voltage amplifier does voltage amplification
current amplifier does current amplification

Is there something like power amplifier or power amplifier is just same as current amplifier?
 
A power amplifier can either a voltage amplifier or a current amplifier.
Typically a power amplifier is a voltage amplifier, such as an audio speaker amp.
 
okay
ASSUME:if suppose a load having low impedance ,then power amplifier want to amplifies the current to drive the speaker
ASSUME:if suppose a load having high impedance ,then power amplifier want to amplifies the voltage to drive the speaker
am i right?
 

No, if anything it does both at all times - the input to the amplifier is a small voltage and a small current, the output to the speaker will be higher voltage and higher current.

However, if there's no load (or a high impedance load) then no current (or little current) will flow.

As with everything else, the current depends on what the load 'wants', the amplifier just has to provide the capability to supply that (whether it's used or not).
 
you mean it all depends what the load needs,we cannot decide that low impedance load need high current and high impedance load need high voltage?
 
An RF power amp is rated for std load of 50 or 75 Ohms ( video)
Audio power Amp is may be rated for different loads e.g. 4-8-16 Ohm

You can figure out max current or max voltage from rated load, but you cannot assume what the maximum voltage or current is for open and short circuit.

Power Amps are always rated for a fixed load and you need to make assumptions for different loads on limitations or read specs or ask .
 
Typically power amplifiers are voltage amplifiers and the output current (and power) depend upon the output voltage and the output load resistance. You just need to design the output stage so that it can provide the necessary current for the rated power and load resistance.
 
normally the output impedance of a typical PA is ~0.1 to 10% or ~1% of rated load, so voltage does not fluctuate with load changes and affects efficiency. Lower is better.

A DC power Supply is the same. e.g. wall- transformer 10%, lab supply 0.1%

Naturally load R affects power used.
 
Nigel Goodwin said:
I would suggest the clue is in the name - 'POWER' amplifier
Click to expand...
Not sure I follow your "clue".
My intention was to differentiate between a voltage amp and a current amplifier (i.e. voltage-controlled constant-current amp) which can also be a power amp, Apparently that wasn't clear.
 
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