Week 02
Current Mirrors and Active Loads
I study differential stages, feedback, filters, and output stages as one connected signal path.
What I connect in this unit
A current mirror copies the VBE or VGS of a diode-connected reference device to reproduce reference current in an output branch. High output resistance makes it an effective active load, but insufficient compliance voltage drives it out of the intended region.
Concept map
- Reference current
- Output resistance
- Active loads
- Compliance voltage
Technical anchor
For matched BJTs with negligible base currents, Iout ≈ Iref; including the Early effect gives the output characteristic a finite slope versus Vout.
How I review it
Calculate the reference resistor for the required Iout, then check that the mirror device remains in its active or saturation region over the full output-voltage range.
Connection to the full course
Unit 2 of 12. Unit numbers follow concept dependencies rather than the historical lecture calendar.