MSSN said:Are u sure that the linear temperature coefficient is of the mirroring ratio and that it isn't the temperature coefficient of the input current.
chang830 said:hi,
Pls. take a look at the attached diagram of a current mirror.
This is a 1:100 current mirror. The NMOS CAP is added here to keep the gate from rippling. In designing/simulation, it is OK. The current ratio is good for all the PVT corners.
But the silicon test is disillusionary. The ratio of current mirror have large excursion from the design value. It is about only 1:80, when the input current is samll, the ratio of current mirror is even low to 1:60.
Another interesting thing is that the ratio of the current mirror have a positive linearly temperature coeffcients.I.e, when the temperature increases, the ratio increased also. While in simulatiion, it is independed with the temperature.
Would anyone help to find any issues with my circuit?
BTW, the process is 0.5um CMOS processs.
Thanks in advance
chang830 said:hi,
Pls. take a look at the attached diagram of a current mirror.
This is a 1:100 current mirror. The NMOS CAP is added here to keep the gate from rippling. In designing/simulation, it is OK. The current ratio is good for all the PVT corners.
But the silicon test is disillusionary. The ratio of current mirror have large excursion from the design value. It is about only 1:80, when the input current is samll, the ratio of current mirror is even low to 1:60.
Another interesting thing is that the ratio of the current mirror have a positive linearly temperature coeffcients.I.e, when the temperature increases, the ratio increased also. While in simulatiion, it is independed with the temperature.
Would anyone help to find any issues with my circuit?
BTW, the process is 0.5um CMOS processs.
Thanks in advance
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