In my integrator design for a ramp output, i need a large resistance value of >500kΩ. Is there anyway to realize this large resistance instead of using a resistor, since resistors take up large die area? Can i use a MOS active load? Kindly advice...thanks!
In my integrator design for a ramp output, i need a large resistance value of >500kΩ. Is there anyway to realize this large resistance instead of using a resistor, since resistors take up large die area? Can i use a MOS active load? Kindly advice...thanks!
Hi, muiyuen
Why not realize this resistor in external?
You can use the following formula to calculate the Ron
Ron=L/[KW(Vgs-Vt-Vds)] and then compare this value with the passive resistor to determin which should be used.
By the way, sometimes put some components outside of the chip is also a good choice.
In my integrator design for a ramp output, i need a large resistance value of >500kΩ. Is there anyway to realize this large resistance instead of using a resistor, since resistors take up large die area? Can i use a MOS active load? Kindly advice...thanks!
I think external resistor maybe a good choice.
Also foundaries provide high resistance process, typically 1k ohms/sq. Still this will cost large area.
Active load may be not good enough, as it's linearity is a problem and long channel MOSFET has parastic caps or so. You can use it if you are sure they wont impact your application.:|
I think external resistor maybe a good choice.
Also foundaries provide high resistance process, typically 1k ohms/sq. Still this will cost large area.
Active load may be not good enough, as it's linearity is a problem and long channel MOSFET has parastic caps or so. You can use it if you are sure they wont impact your application.:|