Hi guys,
I have many identical building blocks, like differential pairs, which are relatively far away from each other (e.g., 100um on the layout) . How to bias all these tail transistors to ensure that a good matching of dc operation point is achieved?
I can think of two ways. First is to use a current mirror for each of the differential pair, and tie all the current mirrors' Vdd together. Another approach is to use a single current mirror and feed the gate voltage to all the tail transistors' gate.
There seems to be another way which feeds the current to instead of voltage to locally generate the bias voltage, but I dont know whether this approach is necessary here.
Thanks!

distribute bias via current methods for two reasons -

Proximity matching and ground noise.