Choose between resistance and capacitance.

[fasto2008]

Helle everyone.
I have to design a circuit MDAC(multiplier digital analog converter) and i have a resistance =20K and a capacitance= 100 Nano.
which kind of resistor and capacitor can i choose?

-Poly resistor or Poly SB resistor or N Diffusion resistor or P Diffusion resistor or N Well resistor.

-NMOS capacitor or PMOS capacitor or CTM capacitor.

Thanks in advance for help

 

[lvlei0309]

100Nano? or pf?

 

[fasto2008]

I mean 100pF.
thanks a lot

 

[leo_o2]

Poly resistor is preferred because of its small voltage coefficiency.
What's CTM cap? I think NMOS/PMOS is not suitable for accurate DAC for nonlinearity. PIP cap, MIM cap or MOM cap is better choice.

 

[mdcui]

20k resistance by poly, will be a big area cost, if not so strict, n-well resistor is also a good choice. and 100pf capacitance can easily be done by mos gate cap (grounding drain and source).

 

[fasto2008]

Hello leo_02,

thank you for your help.
CTM means Cap Top Metal
What do you mean by have small voltage coefficiency ?is there some documents ?
I'm using L-Edit Tanner ,i haven't PIP cap ,MIM cap and MON cap.

 

[lics]

you can choose high-resistance poly which haven't large area. pip cap will suit for you.

 

[drDOC]

You really have to find some electrical parameters of your process.

Resistor: The sheet resistance, temp.co. (TCO) and maybe linearity and matching are important specs.

Capacitor: The cap.density, voltage linearity and leakage and matching are important.

Without knowledge of your process and design everybody will try to advise you to use the smallest devices. High poly and thin oxide mos caps.