@User as Arman said, the value of silicon resistors depends on the geometry, like R = Rho * L / W

Yes I looked up about sheet resistance. Where can I get the sheet resistance for a resistor in PDK ? @User

@User --> https://skywater-pdk.readthedocs.io/en/main/rules/device-details.html#p-poly-precision-resistors . There are values for the other type of resistors as well.

@User Thanks!!I could able to use the generic resistor with required value by changing W and L. Although I could not see sheet resistance values of res_high_po resistors..

you can probably get the sheet resistance (

rsheet

) from the model file, for the

res_high_po

its here (search for this file in your installation):

sky130_fd_pr__res_high_po.model.spice

. It is recommended to use the

res_xhigh_po

version where precision is needed. Consider also that the exact resistance calculation depens on many parameters, the

rsheet*L/W

is just an approximation.

@User For general use we can use generic resistors instead of res_xhigh_po right?

You can use any resistors you want, but each resistor type has its downsides/positives 1. how much they change depending on the PVT cases 2. How high sheet resistance is: higher == less area 3. Low W has downside that vias and connection have impact on final resistance, but you save on area. This is just some of them, depending on what task you are solving you are choosing between: precision and area parameters

Thanks Arman!! I will analyze my circuit and see what resistor suits my requirement.

@User for general use there is also the 'ideal' resistor, in library

devices/res.sym

. This one does not depend on any process, you gust give a value for its resistance. When simulating a real design though at some point you need to replace the ideal components with actual silicon components on the target process (skywater in our case).

Yes Stefan I am simulating a real design so I will be using actual silicon components