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Here's a question for all you EE types out there.In looking at technical information on amplifiers, some are said to have a "complimentary" or "quasi-complimentary" design. Anyone care to offer an explanation on what a complimentary, quasi, and non-complimentary amplifier design actually means?
I've searched around a bit, and I can't find the answer. I'm not too hung up on it, I just like to know what I'm reading.
Follow Ups:
This refers to solid state amplifiers. A complementary design uses PNP and NPN transistors in the output for the positive and negative going sides of the waveform. To do this they need to have matching characteristics. In the early days, it was difficult to find PNP transistors that matched the NPN equivalent. So a design was developed that used a pair of NPN's in the output that gave good +/- wavewform symmetry. This was called quasi-complementary.I think that's substantially correct.
Thanks - that answers my question.As a follow-up, is there really any advantage to a complimentary design? I may be wrong - but it seems like it may be a bit of a wash - poorly matched components will perform poorly, and well-matched will perform well in either design, yes?
There are good and bad examples of both complementary symmetry and quasi-complementary symmetry designs. It's really more a matter of execution than it is a superiority of one circuit topology over another. Although with the availability of complementary pairs of NPN and PNP transistors, complementary circuits are favored.
Here are a few web sites that
should tell you about anything you need to know
about amplifiers.http://www.rocketroberts.com/techart/amp.htm
http://sound.westhost.com/amp-basics.htm#amp-types
http://icc.skku.ac.kr/~won/electro/audiocircuits.html
Complementary and Quasi-complementary output stages are an improvement over the early stages mentioned a few posts earlier - using a huge electrolytic to couple to the speaker. That was the first attempt, using a single-polarity power supply. That was because the DC level at the output, before the capacitor, was 1/2 of the supply voltage.Complementary amplifers use a bi-polar power supply - B+, if we can call it that in SS, is for example, +48 V and -48 V. That allows direct coupling to the load (speaker) since the DC value (called offset) at the output is zero.
Now if someone would only develop a truly complimentary amplifier. Meaning "Take one - it's on us." Guess I've had enuf of the eggnog for this season - I'm hallucinating.
Pat Tobin
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