Mismatch analysis of bandgap

[andrabi]

bandgap vt mismatch

Does any body have papers on mismatch analysis of apamp based bandgap...

thanks

 

[smartdream]

pelgrom analysis of resistor mismatch

Hi, the attached reference maybe can help you !

 

[andrabi]

thanks a lot ..i already had the paper.. but this doesnt analyse the conventional bandgap with opamp an all..thanks anyway

 

[lunren]

hi, If you want to analyse the mismatch of Band gap, the mismatch parameters from the foundry are needed.

For example, the 3.3V PMOS Vtsat mismatch parameter is 4.9mV*um. If you want to know the Vt mismatch of a PMOS current mirror with size of W=10um, L=5um, the Vt mismatch equals to 4.90mV*um/sqrt(10um*5um)=0.693uV.

Normally the mosfet mismatch expresses as: sigma=slope/sqrt(W*L), the slope has a unit of mV*um.
the resistor mismatch expresses as: sigma=slope/sqrt(Weffe*Leffe), the slope has a unit of %.W: resistor width, Weff = W-ΔW, L: resistor length; Leff = L-ΔL.

With these two equations and the mismatch parameters, you can calculate the vt mismatch and resistor mismatch of you circuitry.

 

[smartdream]

hi, If you want to analyse the mismatch of Band gap, the mismatch parameters from the foundry are needed.

For example, the 3.3V PMOS Vtsat mismatch parameter is 4.9mV*um. If you want to know the Vt mismatch of a PMOS current mirror with size of W=10um, L=5um, the Vt mismatch equals to 4.90mV*um/sqrt(10um*5um)=0.693uV.

Normally the mosfet mismatch expresses as: sigma=slope/sqrt(W*L), the slope has a unit of mV*um.
the resistor mismatch expresses as: sigma=slope/sqrt(Weffe*Leffe), the slope has a unit of %.W: resistor width, Weff = W-ΔW, L: resistor length; Leff = L-ΔL.

With these two equations and the mismatch parameters, you can calculate the vt mismatch and resistor mismatch of you circuitry.

when simulation, I usually consider 3-sigma of mismatch, which mentioned by Lunren multiply a factor 3.
Just FYI.

 

[Vamsi Mocherla]

Hey,why dont you download the paper "Matching of MOS Transistors" by Pelgrom. It is very useful and is also available somewhere on the board

 

[andrabi]

thanks alot for the help..but then wat i exactly want is the expression for the mismatch effect in the o/p current or voltage in the bgap due to transistors..and then i ll put the values from foundry to get the spread