Hi,
I'm trying to figure out how to implement a Gm stage. I understand the basic idea - voltage in, current out - and I've seen some figures like (a) and (b) shown in the following diagram, ie. a differential pair with no load representing a Gm stage:
But I'm not sure what exactly to do with this differential pair with no load. I Can I just use the iout+/- from the differential pair directly as the inputs to the next stage? Or do I need a load for the differential pair? And what could I use as the load? I thought about a current mirror, as in (c), but that means it's just an voltage amplifier - the current never goes "out" of this stage, it just gets redistributed between the input transistors. This seems wrong (???).
Perhaps some DC current sources (with common mode feedback for the biasing), as in (d). Then the iout current due to a change in Vin is forced out to the load? But isn't this just a differential amplifier?
Thanks for your help,
Ted