hdmi
Junior Member level 3
current mirror +ckt
The attached circuit is a bias circuit for a folded cascode CMOS Opamp, I was applying the gm/Id methodology and design charts to do the transistor sizing. The process technology is 0.18um and the supply voltages VDD=0.9v, VSS=-0.9V.
While M12 and M17 are alwasy in sat, and M15 also seems to be easy to be made in Saturation, I don't seem to be able to make M13, M14 and M16 all operate in Saturation regions, and the design charts I pre-characterized doesn't seem to help much either. Could anyone shed some light on the rational way when sizing the transistors so that all devices will be in saturation regions? Also can anyone explain what could go wrong from gm/Id methodology and the design charts, and what can I do when I don't get what I expect from the design charts?
Thanks in advance.
P.S. I was using L=0.5um for all transistors and I was making gm/Id = 4 except for M15 which I chose the gm/Id=5.
The attached circuit is a bias circuit for a folded cascode CMOS Opamp, I was applying the gm/Id methodology and design charts to do the transistor sizing. The process technology is 0.18um and the supply voltages VDD=0.9v, VSS=-0.9V.
While M12 and M17 are alwasy in sat, and M15 also seems to be easy to be made in Saturation, I don't seem to be able to make M13, M14 and M16 all operate in Saturation regions, and the design charts I pre-characterized doesn't seem to help much either. Could anyone shed some light on the rational way when sizing the transistors so that all devices will be in saturation regions? Also can anyone explain what could go wrong from gm/Id methodology and the design charts, and what can I do when I don't get what I expect from the design charts?
Thanks in advance.
P.S. I was using L=0.5um for all transistors and I was making gm/Id = 4 except for M15 which I chose the gm/Id=5.