I have some trouble with learn about low power cascode structure, I have see some book, but none of them can give more advice and analyse about low power cascode structure.
Someone can give me some advice about this structure?
I have read the Razavi book, but in this book, the shematic is too simple and I have not find a total schematic use low voltage cascode. I can not find bias part schematic, so I want search a total schematic.
its a simple high swing cascode, its used because in a simple current mirror the mirroring error due to vds mismatch is very high. But when you use a cascode structure the vds of the bottom(mirroring)transistor is being controlled by the cascode transistor and hence when this current is mirrored the mirroring error is going to be negligible.just put this circuit in cadence and try tweaking the sizes from the textbook sizes , you will understand what is happenning.
its a simple high swing cascode, its used because in a simple current mirror the mirroring error due to vds mismatch is very high. But when you use a cascode structure the vds of the bottom(mirroring)transistor is being controlled by the cascode transistor and hence when this current is mirrored the mirroring error is going to be negligible.just put this circuit in cadence and try tweaking the sizes from the textbook sizes , you will understand what is happenning.
Yiu can find somuch data in books and papers for analysis. Iout and Iref need not have same value and its a high swing current mirror. analytically Gray and Holberg are better
its simple, set the gate voltage of M2,M4, to 2vdsat+vth, so that vds of the mirroring transistors are equal.For generating this bias voltage of 2vdat+vth, you can use a transistor of 1/4 the width of M1,M2,M3,M4(assuming M1,M2,M3,M4 are of equal size).