Week 01
Differential Pair Foundations
I study differential stages, feedback, filters, and output stages as one connected signal path.
What I connect in this unit
A differential pair amplifies the difference between its inputs and rejects their shared common-mode component. The tail current establishes both device operating points, and the ratio of differential to common-mode gain defines CMRR.
Concept map
- Differential mode
- Common mode
- Tail current
- Common-mode rejection ratio
Technical anchor
For an ideal symmetric BJT pair at vid = 0, each collector carries Itail/2, and the small-signal single-ended transconductance is approximately gm/2.
How I review it
Sketch collector responses for equal-and-opposite inputs and for inputs moving together, separating differential gain from common-mode residue.
Connection to the full course
Unit 1 of 12. Unit numbers follow concept dependencies rather than the historical lecture calendar.