Analog and mixed-signal engineers who design complex and precision circuits andunerestimate the value of the humble current mirror will be interested to learn that swapping out the tail resistor in a differential pair for a current mirror more than doubles common mode rejection.
Going from a decent 35 dB to a noise-crushing 93 dB, this simple but clever hack means that sensitive, low-level signal work can be achieved more easily on a breadboard, without having to wrestle with mismatched transistors or the vagaries of temperature stability.
It is worth watching the YouTube video by Kevin, which provides both a history lesson on this circuit and a practical engineering guide to using it in a real application, along with GitHub schematics of the demo circuits.
