The current I in the circuit below have the the value independent to the supply voltage. You can mirror it (using the NMOS transistors) and use it as a current source.
The current I in the circuit below have the the value independent to the supply voltage. You can mirror it (using the NMOS transistors) and use it as a current source.
u can use cascode current mirrors
there are three types of cascode current mirrors .. with a liberty of swing that u can want ... low swing and high swing.
these current mirrors mirror to a least extent of error with voltage across the current mirror (obvious : provided all are in saturation region )
If you want to get a constant current, I think there are so many ways. all can be divide two kinds, first , you get a constant voltage which is independent power supply, then use the constant voltage goes throght a resistance with feedback.
another, you can get two kinds current which are PTAT current and CTAT current, then summing them and mirror output.
Using the cascode structures make the current mirrors independent of voltage, but they will eat headroom and need to be carefully oplaced. they can be put in subthreshold also.