Measure leakage using HSPICE

when i am measuring the total power in one clock cycle, it is coming less than the leakage current that means dynamic current is negative. what can be the problems in the circuit. thanks

Hi Gaurav, Connect a additional zero volt source before the gate input to find out gate leakage current. Gate oxide leakage is basically depends on the gate voltage, hence more the gate voltage more will be gate leakage. Follow the same procedure for calculating subthreshold leakage by connecting a zero voltage source at the source line, but here make sure you are keeping gate voltage slightly less then the threshold voltage of the device. If you are looking to find out total leakage current for a given ckt, push ur ckt into standby mode and find out the current through the supply. That will be your total standby( leakage ) current. Leakage power will be simply product ot supply voltage and the total leakage(standby) current. Others , please correct me if i m wrong. Chandan

You gave the solution for leakage power. But how do we get the leakage current from that?

Hi, Dont give any input to your CMOS circuit (or just give an initial condition for input,output). Ex: If its a RAM chip , dont select any memory cell. Operate the circuit in such situation and calculate the power consumed(Vdd * current being drawn from Vdd ). current will be more or less constant as u r not doing any switching . Nand gates etc will be off and hence what u get is pure leakage power. BSIM3 params r modelled for subthreshold behaviour too , so should be fine if u use them while calculating this. ex: nand gate. give initial condition for input = low, output = high. thats all. dont give any input during ur transient analysis. and calc the power consumed. i am just guessing...hope this is correct.