always assume

No. The use of the word, "always" makes the answer either almost useless or it makes the answer require lots and lots of explanation. Please be stingy about using absolutes or all-encompassing words. There are so many ways and objectives to making amplifiers that, basically, there ain't no, "always".

There are also devices that are CCVS (current controlled voltage source) that could have an amplified voltage as output. Are they also called voltage amplifiers?

They are called, "current controlled voltage sources". They could have an amplified voltage as the output, and they might not. What you do with them determines whether they are voltage amplifiers.

The path from book learning to practical application has many avenues. This is a good site for exploring those avenues. You will get help here. Just try to avoid absolutes and try to keep your questions one at a time. Even a seemingly simple question can require a lot of explanation. A dozen questions in one post discourages attempts to answer you.

 

.........So, should we always assume that the input signal connects to the amplifier input in series and the load connects to the amplifier output in series as well?..............

For determining voltage drops you can view it that way; the source impedance is in series with the input impedance.

...... There are also devices that are CCVS (current controlled voltage source) that could have an amplified voltage as output. Are the also called voltage amplifiers?..........

NO, current controlled voltage sources, are exactly as you describe. They are like functional blocks. You can't amplify apples and get oranges. You can amplify voltage to get a higher voltage, you can amplify current to get a higher current. If you input a voltage and it controls a current then, this is a conversion, not an amplification.

 

They are called, "current controlled voltage sources".

Also sometimes called a 'transimpedance', as opposed to a VCCS which may be called a 'transconductance'.

 

Hi Lestraveled,

There are circuits involving op-amps that are called voltage-to-current converter (and vice versa). As you mention, they are converters. But what does it mean to "convert a current into a voltage"?

Clearly, if we get a voltage, we can always get a current (of different magnitude) by inserting a resistor with a certain resistance...

 

Also, this link was useful:

https://en.wikibooks.org/wiki/Circuit_Theory/Dependent_sources

As Lestraveled points out,

• Current controlled current source (CCCS) is a current amplifier (input impedance= 0, output impedance=in)
• Voltage controlled voltage source (VCVS) is a voltage amplifier (input impedance= inf, output impedance=0)
• Current controlled voltage source (CCVS) is called a tranresistance amplifier (input impedance= 0, output impedance=0)
• VCCS is a transconductance amplifier (input impedance= inf , output impedance= inf)

Thanks!

 

Most of what is said here is a bunch of baloney.

there is some confusion, I believe:

1) An IDEAL current source has infinite output Z.
2) An ideal voltage source has an output Z of Zero

So, far no mention of amplification or input Z because there isn't any.

A voltage source can be modeled as a current source in parallel with a resistor.
A current source can be modeled as a voltage source in series with a resistor.
Thank Thevinen and Norton for that. They have Theorems named after them.

An audio amplifier does have an output Z, but it's usually expressed as "Damping factor" = Nominal output Z it's designed to drive/output Z 100 is a good number.

With valve audio amplifiers it was necessary to "transform" the high output Z of the tube (low current/high voltage) to a high current/low voltage. This was done with a transformer.

Impedance matching is necessary at RF frequencies because the small value of capacitance and the high frequency makes Xc come into play.
In this case we want the load to look purely resistive. Capacitance cancels the effects of inductance and vice versa. 50 ohms is a common impedance.

At RF frequencies, there can be reflections in the cable. We don't want that. RF is conducted only on the skin of the conductor to a certain depth. In some amps, the "wires" are silver plated copper TUBES.

An audio amps input Z is about 10K for consumer and 600 ohms for professional. Professional costs more to build. Professional equipment uses a "balanced" input. Plus and minus below and above ground. This eliminates ground loops.

An output of some audio piece of equipment used as an input to another might experience some attenuation. So, profession stuff is usually designed to output a certain voltage into 600 ohms. If we use a low output Z stage at low current it costs less. We can easily do a 50 ohm output Z into 10K with a small amount of current (less cost).

For power supplies, you need to read this https://www.google.com/url?sa=t&rct...fOdZ_-Q1QmLQYKyDQ&sig2=xGsbYaJFfNnh1I1rzBXJqg

A CC supply may not be close to an ideal Current source in the strict sense of the word.

There is always measurement errors.