I wanted to design a switch for switch cap circuit and hence wanted to determine the on resistance of the switch. I know this question has been already asked in the previous threads like
http://www.designers-guide.org/Forum/YaBB.pl?num=1176261122After reading this thread I made a testbench to get the feeling of ron. but still I get confused between the DC resistance (say large signal: here I say it R_nmos) and ron(given by model). In the testbench R_nmos is given by:
R_nmos=((v("/dc" ?result "dc") - v("/v_dco" ?result "dc")) / i("/R1/PLUS" ?result "dc")).
Then I made parametric simulation to see the ron. What I have found that R_nmos is different than the ron. Could you explain me why it is like so?
Is there is something wrong in testbench? or am I missing some fundamentals?
PS:Here I am using ams high voltage transistor in 350nm. And the bias resisto R1=1G(ideal)