Why we are moving from ordinary amplifiers to operational amplifiers?

Question

Why we are moving from ordinary amplifiers to operational amplifiers?

Answer 1

"Ordinary amplifiers"? Do you mean A class, AB class, C class amplifiers? That is traditional, discrete component - either semiconductor (transistor, FET) or valve - amplifiers? If so, then moving toward op-amps is simple: they have a much greater slew rate (rate of change, the amp's ability to react to quickly creating an amplified signal from the input signal), better energy efficiency (especially with CMOS)... mind you, IC op amps have been around for quite some time; the LM741 single op amp IC has been with us for well over twenty-five years. Modern Quad op amps built in to larger, monolithic IC packages are now much more efficient than the early types and, with their inherently stable and efficient makeup, far easier to produce to achieve superior sound quality.

Answer 2

Analog amplifier (tube) needs about one hundred volts of DC, while operational one usually about 15 (and there are ones which work on as low as 5 volts or even less). And it's smaller, cheaper and has longer life. Tubes require heating inside and cooling outside, which eats additional power.

So in a simple device, you can save some size, price and avoid use of high voltage by using an op amp. You can't operate a tube on batteries, for example. And the op amps have evolved to provide enough quality of amplification for most purpose.

However, the highest quality devices still rely on the former.

Edit: If you meant some transistor circuits for the analog amplifier, then the answer is that op amp contains basically the same, only integrated. Then it has only advantages: it's smaller, cheaper, simpler to use and often even better because it contains more complicated circuitry, evolved and enhanced during years of development.

The use for digital signals is just one usage for an op amp. Besides, it is a normal amplifier which can be used for amplifying sound or anything equally well. Its disadvantage is that most op amps are made for frequencies less than about 1 MHz and work bad (distort, damp, phase shift, ...) for high frequencies. Then one either designs an amplifier of his own for the given purpose or simply looks for a special op amp.

Hope this helps!

Answer 3

we are still using ordinary amplifiers

they both do different jobs ordinary amplifiers work great for analog signals and operational amplifiers work better for digital

Answer 4

They are flexible, cheap, and computationally simple.  But 'ordinary' amplifiers are still used for most purposes, and designed for the specific purpose.  You get better circuit cost-performance at the price of higher design cost.