Holger Vogt
8 years ago
2 changed files with 268 additions and 0 deletions
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Perform Monte Carlo simulation in ngspice |
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* 25 stage Ring-Osc. BSIM3 or 4 with statistical variation of model parameters |
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* Model parameters are varied according to the PDK selection. |
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* Tested with 3 different commercial HSPICE libraries from 2 vendors. |
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* To be started with script MC_ring_ts.sp |
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.options noacct seedinfo |
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vin in out dc 0.5 pulse 0.5 0 0.1n 5n 1 1 1 |
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vdd dd 0 dc 3.3 |
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vss ss 0 dc 0 |
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ve sub 0 dc 0 |
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vpe well 0 dc 3.3 |
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* transistors to be selected according to the library (here: p33ll and n33ll or pch_5_mac and nch_5_mac |
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* or pe3 and ne3 or p1 and n1 (these models see below)) |
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.subckt inv1 dd ss sub well in out |
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*XMP1 out in dd well p33ll w=5u l=800n m=3 nf=1 ad=1.35p as=1.35p pd=9.6u ps=9.6u mosmis_mod=1 |
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*XMN1 out in ss sub n33ll w=5u l=800n m=1 nf=3 ad=0.9p as=0.9p pd=6.6u ps=6.6u mosmis_mod=1 |
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*XMP1 out in dd well pch_5_mac w=5u l=800n m=3 nf=1 ad=1.35p as=1.35p pd=9.6u ps=9.6u mosmis_mod=1 |
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*XMN1 out in ss sub nch_5_mac w=5u l=800n m=1 nf=3 ad=0.9p as=0.9p pd=6.6u ps=6.6u mosmis_mod=1 |
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*XMP1 out in dd well pe3 w=5u l=800n m=3 nf=1 ad=1.35p as=1.35p pd=9.6u ps=9.6u mosmis_mod=1 |
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*XMN1 out in ss sub ne3 w=5u l=800n m=1 nf=3 ad=0.9p as=0.9p pd=6.6u ps=6.6u mosmis_mod=1 |
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MP1 out in dd well p1 w=5u l=800n m=3 ad=1.35p as=1.35p pd=9.6u ps=9.6u |
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MN1 out in ss sub n1 w=5u l=800n m=1 ad=0.9p as=0.9p pd=6.6u ps=6.6u |
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.ends inv1 |
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.subckt inv5 dd ss sub well in out |
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xinv1 dd ss sub well in 1 inv1 |
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xinv2 dd ss sub well 1 2 inv1 |
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xinv3 dd ss sub well 2 3 inv1 |
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xinv4 dd ss sub well 3 4 inv1 |
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xinv5 dd ss sub well 4 out inv1 |
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.ends inv5 |
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xinv1 dd ss sub well in out5 inv5 |
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xinv2 dd ss sub well out5 out10 inv5 |
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xinv3 dd ss sub well out10 out15 inv5 |
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xinv4 dd ss sub well out15 out20 inv5 |
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xinv5 dd ss sub well out20 out inv5 |
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xinv11 dd 0 sub well out buf inv1 |
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cout buf ss 0.2pF |
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*** Model library files. |
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* Add your library here |
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* Chose the transistors for XMP1 and XMN1 accordingly |
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*.lib "jc_usage.l" MC_LIB |
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*.lib "my_ts_usage.l" MC_LIB |
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*.lib "x_usage.l" MC_LIB |
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* or use the BSIM3 model with internal parameters except Vth0 |
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* that varies the threshold voltage +-3 sigma around a mean of +-0.6V |
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.model p1 PMOS version=3.3.0 Level=8 Vth0=agauss(-0.6, 0.1, 3) |
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.model n1 NMOS version=3.3.0 Level=8 Vth0=agauss(0.6, 0.1, 3) |
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.end |
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@ -0,0 +1,212 @@ |
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Perform Monte Carlo simulation in ngspice |
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* 25 stage Ring-Osc. BSIM3 or 4 with statistical variation of model parameters |
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* Model parameters are varied according to the PDK selection. |
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* Tested with 3 different commercial HSPICE libraries from 2 vendors. |
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* Add your library to mc_ring_circ.net and choose transistors accordingly. |
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* Add the library path to the .LIB statement. |
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* A simple BSIM3 inverter R.O. serves as an MC example. |
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.options noacct |
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vin in out dc 0.5 pulse 0.5 0 0.1n 5n 1 1 1 |
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vdd dd 0 dc 3.3 |
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vss ss 0 dc 0 |
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ve sub 0 dc 0 |
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vpe well 0 dc 3.3 |
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* transistors to be selected according to the library (here: p33ll and n33ll or pch_5_mac and nch_5_mac |
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* or pe3 and ne3 or p1 and n1 (these models see below)) |
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.subckt inv1 dd ss sub well in out |
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*XMP1 out in dd well p33ll w=5u l=800n m=3 nf=1 ad=1.35p as=1.35p pd=9.6u ps=9.6u mosmis_mod=1 |
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*XMN1 out in ss sub n33ll w=5u l=800n m=1 nf=3 ad=0.9p as=0.9p pd=6.6u ps=6.6u mosmis_mod=1 |
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XMP1 out in dd well pch_5_mac w=5u l=800n m=3 nf=1 ad=1.35p as=1.35p pd=9.6u ps=9.6u mosmis_mod=1 |
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XMN1 out in ss sub nch_5_mac w=5u l=800n m=1 nf=3 ad=0.9p as=0.9p pd=6.6u ps=6.6u mosmis_mod=1 |
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*XMP1 out in dd well pe3 w=5u l=800n m=3 nf=1 ad=1.35p as=1.35p pd=9.6u ps=9.6u mosmis_mod=1 |
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*XMN1 out in ss sub ne3 w=5u l=800n m=1 nf=3 ad=0.9p as=0.9p pd=6.6u ps=6.6u mosmis_mod=1 |
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*MP1 out in dd well p1 w=5u l=800n m=3 ad=1.35p as=1.35p pd=9.6u ps=9.6u |
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*MN1 out in ss sub n1 w=5u l=800n m=1 ad=0.9p as=0.9p pd=6.6u ps=6.6u |
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.ends inv1 |
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.subckt inv5 dd ss sub well in out |
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xinv1 dd ss sub well in 1 inv1 |
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xinv2 dd ss sub well 1 2 inv1 |
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xinv3 dd ss sub well 2 3 inv1 |
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xinv4 dd ss sub well 3 4 inv1 |
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xinv5 dd ss sub well 4 out inv1 |
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.ends inv5 |
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xinv1 dd ss sub well in out5 inv5 |
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xinv2 dd ss sub well out5 out10 inv5 |
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xinv3 dd ss sub well out10 out15 inv5 |
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xinv4 dd ss sub well out15 out20 inv5 |
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xinv5 dd ss sub well out20 out inv5 |
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xinv11 dd 0 sub well out buf inv1 |
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cout buf ss 0.2pF |
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*** Model library files. |
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* Add your library here (full path required, or path relative to path |
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* of ngspice executable (interactive mode), or relative to path of |
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* input file (batch mode)) |
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* Chose the transistors for XMP1 and XMN1 according to the library |
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*.lib "jc_usage.l" MC_LIB |
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*.lib "../../../various/lib-test/my_usage.l" MC_LIB |
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.lib "D:\Spice_general\tests\lib-test\ts14\my_ts_usage.l" MC_LIB |
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*.lib "x_usage.l" MC_LIB |
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* or use the BSIM3 model with internal parameters except Vth0 |
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* that varies the threshold voltage +-3 sigma around a mean of +-0.6V |
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*.model p1 PMOS version=3.3.0 Level=8 Vth0=agauss(-0.6, 0.1, 3) |
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*.model n1 NMOS version=3.3.0 Level=8 Vth0=agauss(0.6, 0.1, 3) |
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.control |
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let mc_runs = 10 $ number of runs for monte carlo |
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let run = 0 $ number of actual run |
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set curplot = new $ create a new plot |
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set curplottitle = "Transient outputs" |
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set plot_out = $curplot $ store its name to 'plot_out' |
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set curplot = new $ create a new plot |
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set curplottitle = "FFT outputs" |
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set plot_fft = $curplot $ store its name to 'plot_fft' |
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set curplot = new $ create a new plot |
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set curplottitle = "Oscillation frequency" |
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set max_fft = $curplot $ store its name to 'max_fft' |
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let mc_runsp = mc_runs + 1 |
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let maxffts = unitvec(mc_runsp) $ vector for storing max measure results |
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let halfffts = unitvec(mc_runsp)$ vector for storing measure results at -40dB rising |
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unlet mc_runsp |
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set mc_runs = $&mc_runs $ create a variable from the vector |
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let seeds = mc_runs + 2 |
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setseed $&seeds |
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unlet seeds |
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save buf $ we just need buf, save memory by more than 10x |
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* run the simulation loop |
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* We have to figure out what to do if a single simulation will not converge. |
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* There is now the variable sim_status, that is 0 if simulation ended regularly, |
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* and 1 if the simulation has been aborted with error message '...simulation(s) aborted'. |
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* Then we skip the rest of the run and continue with a new run. |
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dowhile run <= mc_runs |
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set run = $&run $ create a variable from the vector |
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* run=0 simulates with nominal parameters |
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if run > 0 |
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echo |
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echo * * * * * * |
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echo Source the circuit again internally for run no. $run |
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echo * * * * * * |
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setseed $run |
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mc_source $ re-source the input file |
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else |
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echo run no. $run |
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end |
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echo simulation run no. $run of $mc_runs |
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tran 100p 1000n 0 |
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echo Simulation status $sim_status |
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let simstat = $sim_status |
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if simstat = 1 |
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if run = mc_runs |
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echo go to end |
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else |
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echo go to next run |
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end |
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destroy $curplot |
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goto next |
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end |
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* select stop and step so that number of data points after linearization is not too |
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* close to 8192, which would yield varying number of line length and thus scale for fft. |
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* |
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set dt0 = $curplot |
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* save the linearized data for having equal time scales for all runs |
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linearize buf $ linearize only buf, no other vectors needed |
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set dt1 = $curplot $ store the current plot to dt (tran i+1) |
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setplot $plot_out $ make 'plt_out' the active plot |
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* firstly save the time scale once to become the default scale |
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if run=0 |
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let time={$dt1}.time |
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end |
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let vout{$run}={$dt1}.buf $ store the output vector to plot 'plot_out' |
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setplot $dt1 $ go back to the previous plot (tran i+1) |
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fft buf $ run fft on vector buf |
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let buf2=db(mag(buf)) |
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* find the frequency where buf has its maximum of the fft signal |
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meas sp fft_max MAX_AT buf2 from=0.05G to=0.7G |
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* find the frequency where buf is -40dB at rising fft signal |
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meas sp fft_40 WHEN buf2=-40 RISE=1 from=0.05G to=0.7G |
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* store the fft vector |
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set dt2 = $curplot $ store the current plot to dt (spec i) |
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setplot $plot_fft $ make 'plot_fft' the active plot |
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if run=0 |
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let frequency={$dt2}.frequency |
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end |
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let fft{$run}={$dt2}.buf $ store the output vector to plot 'plot_fft' |
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* store the measured value |
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setplot $max_fft $ make 'max_fft' the active plot |
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let maxffts[{$run}]={$dt2}.fft_max |
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let halfffts[{$run}]={$dt2}.fft_40 |
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destroy $dt0 $dt1 $dt2 $ save memory, we don't need this plot (spec) any more |
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label next |
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remcirc |
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let run = run + 1 |
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end |
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***** plotting ********************************************************** |
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if $?batchmode |
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echo |
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echo Plotting not available in batch mode |
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echo Write linearized vout0 to vout{$mc_runs} to rawfile $rawfile |
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echo |
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write $rawfile {$plot_out}.allv |
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rusage |
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quit |
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else |
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plot {$plot_out}.vout0 $ just plot the tran output with run 0 parameters |
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setplot $plot_fft |
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plot db(mag(ally)) xlimit 0 1G ylimit -80 10 |
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* |
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* create a histogram from vector maxffts |
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setplot $max_fft $ make 'max_fft' the active plot |
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set startfreq=50MEG |
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set bin_size=1MEG |
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set bin_count=100 |
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compose osc_frequ start=$startfreq step=$bin_size lin=$bin_count $ requires variables as parameters |
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settype frequency osc_frequ |
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let bin_count=$bin_count $ create a vector from the variable |
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let yvec=unitvec(bin_count) $ requires vector as parameter |
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let startfreq=$startfreq |
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let bin_size=$bin_size |
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* put data into the correct bins |
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let run = 0 |
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dowhile run < mc_runs |
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set run = $&run $ create a variable from the vector |
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let val = maxffts[{$run}] |
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let part = 0 |
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* Check if val fits into a bin. If yes, raise bin by 1 |
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dowhile part < bin_count |
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if ((val < (startfreq + (part+1)*bin_size)) & (val > (startfreq + part*bin_size))) |
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let yvec[part] = yvec[part] + 1 |
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break |
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end |
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let part = part + 1 |
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end |
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let run = run + 1 |
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end |
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* plot the histogram |
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set plotstyle=combplot |
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let counts = yvec - 1 $ subtract 1 because we started with unitvec containing ones |
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plot counts vs osc_frequ |
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* calculate jitter |
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let diff40 = (vecmax(halfffts) - vecmin(halfffts))*1e-6 |
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echo |
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echo Max. jitter is "$&diff40" MHz |
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end |
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rusage |
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* quit |
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.endc |
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.end |
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