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https://designers-guide.org/forum/YaBB.pl Design >> Analog Design >> How to Calculate DC Av,Gm, ..etc characteristics https://designers-guide.org/forum/YaBB.pl?num=1180083589 Message started by kiran123 on May 25th, 2007, 1:59am |
Title: How to Calculate DC Av,Gm, ..etc characteristics Post by kiran123 on May 25th, 2007, 1:59am Hi Experts, I have done some spectre simulations (using MDL feature) on simple basic circuit as shown in figure attached , my intension is to find DC voltage gain and Gm of NMOS using Resistive load connected to POWER supply. when i compared the results say gm i.e by using buil in feature X1.M0:gm and actual calculated one i.e ( X1.Mo:ids/V(IN) ) by varying the V(IN) i.e Gate Voltage , i observed there is diference between these two values and i wanted to know what this built in gm stands for and the one explicitely i am calculating, similarly for 3 types of Av 's that i am calculating below is the MDL deck alias measurement DC_Exp { run DC_op export real GM = X1.M0:gm export real GM_cal = Idrive/VGS export real GM_cal_in = Idrive/V(IN) export real VGS = X1.M0:vgs export real VTH = X1.M0:vth export real IDS = X1.M0:ids export real Idrive = I(X1.R0) export real Av = GM * 99.9999 export real Av_cal = GM_cal * 99.9999 export real Av_volt = V(OUT)/V(IN) } run DC_Exp printing each above values at each step of variable input voltage So let me know if i am wrong in doing above kind of measurement , since i am doing DC i have not done any Av = dVout/ dVin kind results And also teh attached figure shows the simulation graph between Vds Vs Ids , in my simulations the Ids not becoming constant but keep increasing w.r.t Vgs where as Vds is constant through out my experiment It would be really great help if you can give me idea on how to actually calculate those above Thanks & Best Regards Kiran |
Title: Re: How to Calculate DC Av,Gm, ..etc characteristi Post by kiran123 on May 25th, 2007, 2:07am because of Max size it could not attached the Picture , now i attached it in Zip format Thanks |
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