How does one go about finding the Avth (threshold mismatch) of the devices in this PDK? I am currently trying to calculate threshold voltage mismatch (Av / WL) for a simple flash ADC design that uses strongARM comparators.

By "this PDK" I assume you mean sky130? You can simulate with the mismatch corners (e.g., corner

tt_mm

). Or, if you just want the number for the one parameter, look in the model files. For example, in

$PDK_ROOT/sky130A/libs.ref/sky130_fd_pr/spice/sky130_fd_pr__nfet_01v8__tt.pm3.spice

(substitute appropriate device and process corner), find the line

vth0 =

for the appropriate FET model bin given the W and L values. For the example,

nfet_01v8

model bin

0

, the line is:

+ vth0 = {0.5190093+MC_MM_SWITCH*AGAUSS(0,1.0,1)*(sky130_fd_pr__nfet_01v8__vth0_slope/sqrt(l*w*mult))}

although I am having difficulty figuring out where

sky130_fd_pr__nfet_01v8__vth0_slope

is being defined and included; it is defined in

invariant.spice

(

sky130_fd_pr__nfet_01v8__vth0_slope = 0.003356

) but that seems to be only included in the monte carlo simulation setup. I'm sure it's there somewhere, or else ngspice would halt with an error. The continuous models are done differently and I don't understand how the method differs; the mismatch is captured in a subcircuit parameter

swx_vth

which is then used in computing model parameter

delvto

, while parameter

vth0

itself is constant.

delvto

is not used in the discrete models.