Re: Injected current in current mirror
What do You want to know?
If Iinjected is a constant DC current source, sinking 1µA of current it will result with sinking ≈3µA of current from VDD source and VD2 potential goes down to set OP point of M4 to provide ≈2µA (one for Iinjected current source and second for drain of M2 current source). Due to classic cascode biasing, VD2 with absence of Iinjected is large enough to preserve M2 in saturation after adding Iinjected (in most cases).