003_freq_divider : RF Frequency Divider Schematic Simulation
Minimum Required Versions: Gateway 2.12.8.R, SmartSpiceRF 1.6.3.R
The schematic for Example 3 ( schematic.png ) is a frequency divider design. Since the division factor is 4, the fundamental frequency is set to the output frequency (FUND1=250MegHz) equal to the input frequency (1 GHz) divided by 4. RF input source at 4*FUND1frequency is specified as fourth harmonic stimuli: Vck ck GND DC 0.9 MTS1(0.9 0.0 4) .
In the control file ( freq_divider.ctr), a large number of harmonics (nharm1=40) and an oversampling factor of 2 (oversample=2) are specified to better represent the square-like waveforms produced by this nonlinear circuit.
A Transient Initial Guess (TIG) is set by UseTIG=3. Transient simulation time is defined by TIGtstop=5n. The accuracy option reltol=1e-6 is set to obtain an accurate initial guess.
The quality of the initial guess can be determined by checking the first Newton KCL residual (displayed with annotate=4). The lower the residual numerical value, the better is the initial guess.
The .IPLOT harm_sp vdb0 vdb1 statement is used to interactively plot the spectra for b0 and b1 as the simulation runs. The resulting plot is shown in SmartView ( spectra.png ).
Expanding the transient analysis in the data browser, the waveforms are plotted for nodes b0 and b1 ( transient.png ).
Finally, the RF input stimulus, the RF voltage waveform at node b0 (division by 2), and the RF voltage waveform at node b1 (division by 4) are seen on the RF plot ( RF.png ).
Input Files
freq_divider.ctr
* BSIM4v6 Frequency Devider/4 for HARMONIC analysis * .options nomod acct=2 reltol=1e-6 .global vss vdd * * .HARM FUND1=250MegHz nharm1=40 + oversample = 2 + UseTIG = 3 + TIGtstop = 15n + TIGtmax = 0.1n + annotate=4 + waves * * Results .PROBE v(ck) v(b0) v(b1) .LET harm_sp vdb0='db(v(b0))' vdb1='db(v(b1))' .IPLOT harm_sp vdb0 vdb1 * ** Model: BSIM4.6.0 ** Berkeley SPICE3f5 Compatible ** Lmin=0.02 Lmax=10 Wmin=0.6 Wmax=20 .MODEL NCH NMOS LEVEL = 14 +VERSION = 6.0 BINUNIT = 1 PARAMCHK= 1 MOBMOD = 0 +CAPMOD = 2 IGCMOD = 1 IGBMOD = 1 GEOMOD = 1 +DIOMOD = 1 RDSMOD = 0 RBODYMOD= 0 RGATEMOD= 1 +PERMOD = 1 ACNQSMOD= 0 TRNQSMOD= 0 TEMPMOD = 0 +TNOM = 27 TOXE = 1.8E-009 TOXP = 10E-010 TOXM = 1.8E-009 +DTOX = 8E-10 EPSROX = 3.9 WINT = 5E-009 LINT = 1E-009 +LL = 0 WL = 0 LLN = 1 WLN = 1 +LW = 0 WW = 0 LWN = 1 WWN = 1 +LWL = 0 WWL = 0 XPART = 0 TOXREF = 1.4E-009 +SAREF = 5E-6 SBREF = 5E-6 WLOD = 2E-6 KU0 = -4E-6 +KVSAT = 0.2 KVTH0 = -2E-8 TKU0 = 0.0 LLODKU0 = 1.1 +WLODKU0 = 1.1 LLODVTH = 1.0 WLODVTH = 1.0 LKU0 = 1E-6 +WKU0 = 1E-6 PKU0 = 0.0 LKVTH0 = 1.1E-6 WKVTH0 = 1.1E-6 +PKVTH0 = 0.0 STK2 = 0.0 LODK2 = 1.0 STETA0 = 0.0 +LODETA0 = 1.0 +LAMBDA = 4E-10 +VSAT = 1.1E+005 +VTL = 2.0E5 XN = 6.0 LC = 5E-9 +RNOIA = 0.577 RNOIB = 0.37 +LINTNOI = 1E-009 +TVOFF = 0.0 TVFBSDOFF = 0.0 +VTH0 = 0.25 +K1 = 0.35 K2 = 0.05 K3 = 0 +K3B = 0 W0 = 2.5E-006 DVT0 = 1.8 DVT1 = 0.52 +DVT2 = -0.032 DVT0W = 0 DVT1W = 0 DVT2W = 0 +DSUB = 2 MINV = 0.05 VOFFL = 0 DVTP0 = 1E-007 +DVTP1 = 0.05 LPE0 = 5.75E-008 LPEB = 2.3E-010 XJ = 2E-008 +NGATE = 5E+020 NDEP = 2.8E+018 NSD = 1E+020 PHIN = 0 +CDSC = 0.0002 CDSCB = 0 CDSCD = 0 CIT = 0 +VOFF = -0.15 NFACTOR = 1.2 ETA0 = 0.05 ETAB = 0 +UC = -3E-011 +VFB = -0.55 U0 = 0.032 UA = 5.0E-011 UB = 3.5E-018 +A0 = 2 AGS = 1E-020 +A1 = 0 A2 = 1 B0 = -1E-020 B1 = 0 +KETA = 0.04 DWG = 0 DWB = 0 PCLM = 0.08 +PDIBLC1 = 0.028 PDIBLC2 = 0.022 PDIBLCB = -0.005 DROUT = 0.45 +PVAG = 1E-020 DELTA = 0.01 PSCBE1 = 8.14E+008 PSCBE2 = 5E-008 +FPROUT = 0.2 PDITS = 0.2 PDITSD = 0.23 PDITSL = 2.3E+006 +RSH = 0 RDSW = 50 RSW = 50 RDW = 50 +RDSWMIN = 0 RDWMIN = 0 RSWMIN = 0 PRWG = 0 +PRWB = 6.8E-011 WR = 1 ALPHA0 = 0.074 ALPHA1 = 0.005 +BETA0 = 30 AGIDL = 0.0001 BGIDL = 2.1E+009 CGIDL = 0.0001 +EGIDL = 0.8 AGISL = 0.0002 BGISL = 2.1E+009 CGISL = 0.0002 +EGISL = 0.8 +AIGBACC = 0.012 BIGBACC = 0.0028 CIGBACC = 0.002 +NIGBACC = 1 AIGBINV = 0.014 BIGBINV = 0.004 CIGBINV = 0.004 +EIGBINV = 1.1 NIGBINV = 3 AIGC = 0.012 BIGC = 0.0028 +CIGC = 0.002 AIGS = 0.012 BIGS = 0.0028 CIGS = 0.002 +NIGC = 1 POXEDGE = 1 PIGCD = 1 NTOX = 1 +AIGD = 0.01 BIGD = 0.003 CIGD = 0.0015 +XRCRG1 = 12 XRCRG2 = 5 +CGSO = 6.238E-010 CGDO = 6.238E-010 CGBO = 2.56E-011 CGDL = 2.495E-10 +CGSL = 2.495E-10 CKAPPAS = 0.03 CKAPPAD = 0.03 ACDE = 1 +MOIN = 15 NOFF = 0.9 VOFFCV = 0.02 +KT1 = -0.37 KT1L = 0.0 KT2 = -0.042 UTE = -1.5 +UA1 = 1E-009 UB1 = -3.5E-019 UC1 = 0 PRT = 0 +AT = 53000 +FNOIMOD = 1 TNOIMOD = 0 +JSS = 0.0001 JSWS = 1E-011 JSWGS = 1E-010 NJS = 1 +IJTHSFWD= 0.01 IJTHSREV= 0.001 BVS = 10 XJBVS = 1 +JSD = 0.0001 JSWD = 1E-011 JSWGD = 1E-010 NJD = 1 +IJTHDFWD= 0.01 IJTHDREV= 0.001 BVD = 10 XJBVD = 1 +PBS = 1 CJS = 0.0005 MJS = 0.5 PBSWS = 1 +CJSWS = 5E-010 MJSWS = 0.33 PBSWGS = 1 CJSWGS = 3E-010 +MJSWGS = 0.33 PBD = 1 CJD = 0.0005 MJD = 0.5 +PBSWD = 1 CJSWD = 5E-010 MJSWD = 0.33 PBSWGD = 1 +CJSWGD = 5E-010 MJSWGD = 0.33 TPB = 0.005 TCJ = 0.001 +TPBSW = 0.005 TCJSW = 0.001 TPBSWG = 0.005 TCJSWG = 0.001 +XTIS = 3 XTID = 3 +DMCG = 0E-006 DMCI = 0E-006 DMDG = 0E-006 DMCGT = 0E-007 +DWJ = 0.0E-008 XGW = 0E-007 XGL = 0E-008 +RSHG = 0.4 GBMIN = 1E-010 RBPB = 5 RBPD = 15 +RBPS = 15 RBDB = 15 RBSB = 15 NGCON = 1 +JTSS = 1E-4 JTSD = 1E-4 JTSSWS = 1E-10 JTSSWD = 1E-10 +JTSSWGS = 1E-7 JTSSWGD = 1E-7 +NJTS = 20.0 NJTSSW = 15 NJTSSWG = 6 VTSS = 10 +VTSD = 10 VTSSWS = 10 VTSSWD = 10 +NJTSD = 15.0 NJTSSWD = 20 NJTSSWGD = 6 +TNJTS = 0.1 TNJTSD = 0.05 +VTSSWGS=2 VTSSWGD=2 +XTSS = 0.02 XTSD = 0.02 XTSSWS = 0.02 XTSSWD = 0.02 XTSSWGS = 0.02 XTSSWGD = 0.02 ** Model: BSIM4.6.0 ** Berkeley SPICE3f5 Compatible ** Lmin=0.02 Lmax=10 Wmin=0.6 Wmax=20 .MODEL PCH PMOS LEVEL = 14 +VERSION = 6.0 BINUNIT = 1 PARAMCHK= 1 MOBMOD = 0 +CAPMOD = 2 IGCMOD = 1 IGBMOD = 1 GEOMOD = 1 +DIOMOD = 1 RDSMOD = 0 RBODYMOD= 0 RGATEMOD= 1 +PERMOD = 1 ACNQSMOD= 0 TRNQSMOD= 0 TEMPMOD = 0 +TNOM = 27 TOXE = 1.8E-009 TOXP = 10E-010 TOXM = 1.8E-009 +DTOX = 8E-10 EPSROX = 3.9 WINT = 5E-009 LINT = 1E-009 +LL = 0 WL = 0 LLN = 1 WLN = 1 +LW = 0 WW = 0 LWN = 1 WWN = 1 +LWL = 0 WWL = 0 XPART = 0 TOXREF = 1.8E-9 +SAREF = 5E-6 SBREF = 5E-6 WLOD = 2E-6 KU0 = 4E-6 +KVSAT = 0.2 KVTH0 = -2E-8 TKU0 = 0.0 LLODKU0 = 1.1 +WLODKU0 = 1.1 LLODVTH = 1.0 WLODVTH = 1.0 LKU0 = 1E-6 +WKU0 = 1E-6 PKU0 = 0.0 LKVTH0 = 1.1E-6 WKVTH0 = 1.1E-6 +PKVTH0 = 0.0 STK2 = 0.0 LODK2 = 1.0 STETA0 = 0.0 +LODETA0 = 1.0 +LAMBDA = 4E-10 +VSAT = 1.1E+005 +VTL = 2.0E5 XN = 6.0 LC = 5E-9 +RNOIA = 0.577 RNOIB = 0.37 +LINTNOI = 1E-009 +TVOFF = 0.0 TVFBSDOFF = 0.0 +VTH0 = -0.25 +K1 = 0.35 K2 = 0.05 K3 = 0 +K3B = 0 W0 = 2.5E-006 DVT0 = 1.8 DVT1 = 0.52 +DVT2 = -0.032 DVT0W = 0 DVT1W = 0 DVT2W = 0 +DSUB = 2 MINV = 0.05 VOFFL = 0 DVTP0 = 1E-007 +DVTP1 = 0.05 LPE0 = 5.75E-008 LPEB = 2.3E-010 XJ = 2E-008 +NGATE = 5E+020 NDEP = 2.8E+018 NSD = 1E+020 PHIN = 0 +CDSC = 0.0002 CDSCB = 0 CDSCD = 0 CIT = 0 +VOFF = -0.15 NFACTOR = 1.2 ETA0 = 0.05 ETAB = 0 +VFB = 0.55 U0 = 0.0095 UA = 5.0E-011 UB = 3.5E-018 +UC = -3E-011 +A0 = 2 AGS = 1E-020 +A1 = 0 A2 = 1 B0 = -1E-020 B1 = 0 +KETA = 0.04 DWG = 0 DWB = 0 PCLM = 0.08 +PDIBLC1 = 0.028 PDIBLC2 = 0.022 PDIBLCB = -0.005 DROUT = 0.45 +PVAG = 1E-020 DELTA = 0.01 PSCBE1 = 8.14E+008 PSCBE2 = 5E-008 +FPROUT = 0.2 PDITS = 0.2 PDITSD = 0.23 PDITSL = 2.3E+006 +RSH = 0 RDSW = 50 RSW = 50 RDW = 50 +RDSWMIN = 0 RDWMIN = 0 RSWMIN = 0 PRWG = 0 +PRWB = 6.8E-011 WR = 1 ALPHA0 = 0.074 ALPHA1 = 0.005 +BETA0 = 30 AGIDL = 0.0002 BGIDL = 2.1E+009 CGIDL = 0.0002 +EGIDL = 0.8 AGISL = 0.0003 BGISL = 2.5E+009 CGISL = 0.0003 +EGISL = 0.8 +AIGBACC = 0.012 BIGBACC = 0.0028 CIGBACC = 0.002 +NIGBACC = 1 AIGBINV = 0.014 BIGBINV = 0.004 CIGBINV = 0.004 +EIGBINV = 1.1 NIGBINV = 3 AIGC = 0.012 BIGC = 0.0028 +CIGC = 0.002 AIGS = 0.012 BIGS = 0.0028 CIGS = 0.002 +NIGC = 1 POXEDGE = 1 PIGCD = 1 NTOX = 1 +AIGD = 0.01 BIGD = 0.003 CIGD = 0.0015 +XRCRG1 = 12 XRCRG2 = 5 +CGSO = 6.238E-010 CGDO = 6.238E-010 CGBO = 2.56E-011 CGDL = 2.495E-10 +CGSL = 2.495E-10 CKAPPAS = 0.03 CKAPPAD = 0.03 ACDE = 1 +MOIN = 15 NOFF = 0.9 VOFFCV = 0.02 +KT1 = -0.37 KT1L = 0.0 KT2 = -0.042 UTE = -1.5 +UA1 = 1E-009 UB1 = -3.5E-019 UC1 = 0 PRT = 0 +AT = 53000 +FNOIMOD = 1 TNOIMOD = 0 +JSS = 0.0001 JSWS = 1E-011 JSWGS = 1E-010 NJS = 1 +IJTHSFWD= 0.01 IJTHSREV= 0.001 BVS = 10 XJBVS = 1 +JSD = 0.0001 JSWD = 1E-011 JSWGD = 1E-010 NJD = 1 +IJTHDFWD= 0.01 IJTHDREV= 0.001 BVD = 10 XJBVD = 1 +PBS = 1 CJS = 0.0005 MJS = 0.5 PBSWS = 1 +CJSWS = 5E-010 MJSWS = 0.33 PBSWGS = 1 CJSWGS = 3E-010 +MJSWGS = 0.33 PBD = 1 CJD = 0.0005 MJD = 0.5 +PBSWD = 1 CJSWD = 5E-010 MJSWD = 0.33 PBSWGD = 1 +CJSWGD = 5E-010 MJSWGD = 0.33 TPB = 0.005 TCJ = 0.001 +TPBSW = 0.005 TCJSW = 0.001 TPBSWG = 0.005 TCJSWG = 0.001 +XTIS = 3 XTID = 3 +DMCG = 0E-006 DMCI = 0E-006 DMDG = 0E-006 DMCGT = 0E-007 +DWJ = 0.0E-008 XGW = 0E-007 XGL = 0E-008 +RSHG = 0.4 GBMIN = 1E-010 RBPB = 5 RBPD = 15 +RBPS = 15 RBDB = 15 RBSB = 15 NGCON = 1 +JTSS = 1E-4 JTSD = 1E-4 JTSSWS = 1E-10 JTSSWD = 1E-10 +JTSSWGS = 1E-7 JTSSWGD = 1E-7 +NJTS = 20.0 NJTSSW = 15 NJTSSWG = 4 VTSS = 10 +VTSD = 10 VTSSWS = 10 VTSSWD = 10 +NJTSD = 15.0 NJTSSWD = 20 NJTSSWGD = 6 +TNJTS = 0.1 TNJTSD = 0.05 +VTSSWGS=2 VTSSWGD=2 +XTSS = 0.02 XTSD = 0.02 XTSSWS = 0.02 XTSSWD = 0.02 XTSSWGS = 0.02 XTSSWGD = 0.02 *
Graphics
