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The lecture says that differenial biasing is easier than single ended. Could anyone explain why differential biasing is easier than single-ended one?

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  • \$\begingroup\$ Where in the lecture did you find this term? \$\endgroup\$ – LvW Apr 5 '16 at 20:09
  • \$\begingroup\$ Hi, it is in the page 2 of the lecture. It says "Biasing is easier". \$\endgroup\$ – anhnha Apr 6 '16 at 7:37
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A differential amplifier usually has a tail-current source that sets the bias current of the transistors of the differential pair.

It is usually used in a feedback configuration, thus it can control its own operating point taking advantage of the feedback.

Differential amplifiers are often used in integrated circuits where some kind of reference current is available, that can be replicated using current mirrors. It is thereby possible to set the bias current accurately and determine the operating quite accurately.

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  • \$\begingroup\$ Mario - as you gave an answer, can you please explain what "diff. biasing" means? It must be something else than "biasing a diff. pair" because it was compared with "single ended biasing" - what ever this means. \$\endgroup\$ – LvW Apr 5 '16 at 20:09
  • \$\begingroup\$ @LvW - My assumption was that "diff. biasing" actually should mean "biasing using a diff pair", since it is generally easier to realize than biasing a simple transistor stage ("single ended biasing"). It often goes unnoticed that the diff pair simplifies biasing. \$\endgroup\$ – Mario Apr 5 '16 at 21:01
  • \$\begingroup\$ Independent on the question if biasing of a diff. pair is "easier to realize" (however, I do not agree) I am not sure if this was the core of the question. Perhaps user3126592 can clarify. \$\endgroup\$ – LvW Apr 6 '16 at 7:10
  • \$\begingroup\$ Mario - it seems that the question is related to two possible operational modes of a diff. pair: Single ended (one output node only) vs. differential output. But I am not sure why the author says: "biasing is easier". \$\endgroup\$ – LvW Apr 6 '16 at 8:02

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