baseball07
Newbie level 6
Hi guys. I have a question on a schematic that I am looking at. It is used as a variable current source, however I am just a little confused on how exactly it is working. It is attached. From what I gather, the 2 bits control how much voltage is present on the gate of p-MOS2 via potential dividers. I am a little confused about what the 2 p-MOSFETs are doing. Normally, I have seen current mirrors used as current sources but this is not that configuration.
This is how I see it working, please correct me if I am wrong. When there is voltage present on the gate of p-MOS 2, some current will flow (MOSFET is in triode region) this produces a drain current which is proportional to the drain voltage which is used as the gate voltage for p-MOS1. This in turn produces a drain voltage which is used as the source of p-MOS 2. So it is sort of like a feedback system. Is this correct? What is the advantage of such a circuit? Thanks alot.
This is how I see it working, please correct me if I am wrong. When there is voltage present on the gate of p-MOS 2, some current will flow (MOSFET is in triode region) this produces a drain current which is proportional to the drain voltage which is used as the gate voltage for p-MOS1. This in turn produces a drain voltage which is used as the source of p-MOS 2. So it is sort of like a feedback system. Is this correct? What is the advantage of such a circuit? Thanks alot.