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Resistor in CMOS process

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020170

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Some circuit needs resistor to adjust voltage vallue.

Especially, resistor used in Voltage divider circuit.

In cmos process, process variation of resistor is too large to ignore.

in additional to Aread of Resistor is big compare to NMOS or PMOS

Nevertheless, Why We use Resistor in Voltage divider circuit instead of MOS?

May we use diode-connected MOS in the voltage divider circuit instead of resistors?
 

I think the second order effect of the mos make the accuracy of the voltage very low.

however, the resistor used in Voltage divider circuit has better relative accuracy.
 

in fact , the mismatch in mos transistors is the same with the resisters.
 

I think resistor gives you more flexibility to have a more wide range of voltage from resistive voltage divider. A diode connected MOS is bounded to Vth.
 

As per my exp, the resistance value has to be changed to +/- x% for all other process corners other than typical corner, given by foundary
 

The ratio of resistors is much smaller than any single resistor,

it is acceptable for IC design

Added after 2 minutes:

analog_prodigy said:
As per my exp, the resistance value has to be changed to +/- x% for all other process corners other than typical corner, given by foundary

but they have the same change,

so it has no impact on voltage divider.
 

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