| Electronics > Beginners |
| Issue interpreting AC phase plot |
| (1/4) > >> |
| promach:
I am having some issue interpreting the following AC phase plot. The AC gain plot is ok, rolling off at high frequencies, but what about the --- End quote --- which increases from 0 towards 180 degrees at higher frequencies ? Note: The current input stimulus and feedback resistor is configuring the inverter as a transimpedance amplifier. It’s to avoid disturbing the dc bias. test_cmos_inverter.asc --- Code: ---Version 4 SHEET 1 2264 2956 WIRE 256 -48 240 -48 WIRE 528 -48 256 -48 WIRE 240 0 240 -48 WIRE 256 48 256 -48 WIRE 256 48 240 48 WIRE 192 80 160 80 WIRE 160 160 160 80 WIRE 240 160 240 96 WIRE 240 192 240 160 WIRE 272 192 240 192 WIRE 384 192 272 192 WIRE 112 224 0 224 WIRE 160 224 160 160 WIRE 160 224 112 224 WIRE 240 224 240 192 WIRE 0 272 0 224 WIRE 256 272 240 272 WIRE 528 288 528 -48 WIRE 160 304 160 224 WIRE 192 304 160 304 WIRE 240 352 240 320 WIRE 256 352 256 272 WIRE 256 352 240 352 WIRE 0 416 0 352 WIRE 256 416 256 352 WIRE 256 416 0 416 WIRE 352 416 256 416 WIRE 384 416 384 272 WIRE 384 416 352 416 WIRE 528 416 528 368 WIRE 528 416 384 416 WIRE 352 448 352 416 FLAG 352 448 0 FLAG 112 224 in FLAG 272 192 out SYMBOL nmos4 192 224 R0 SYMATTR InstName M1 SYMATTR Value TSMC180nmN SYMATTR Value2 l=3u w=1.2u SYMBOL voltage 528 272 R0 SYMATTR InstName V1 SYMATTR Value 1.0 SYMBOL pmos4 192 0 R0 SYMATTR InstName M2 SYMATTR Value TSMC180nmP SYMATTR Value2 l=3u w=0.4u SYMBOL current 0 272 R0 WINDOW 123 24 102 Left 2 SYMATTR Value2 AC 1 SYMATTR InstName I1 SYMATTR Value 0 SYMBOL res 256 144 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 2 135 VTop 2 SYMATTR InstName R1 SYMATTR Value 1Meg SYMBOL current 384 192 R0 WINDOW 123 39 50 Left 2 WINDOW 3 68 23 Left 2 SYMATTR Value2 AC 0 SYMATTR InstName I2 SYMATTR Value 0 TEXT 864 176 Left 2 !.op TEXT 872 200 Left 2 !.ac dec 100 1 10g TEXT 816 328 Left 2 !.include tsmc180nmcmos.lib TEXT 808 256 Left 2 !;.dc I1 -165n 165n 1n --- End code --- tsmc180nmcmos.lib --- Code: ---* PSPICE TSMC180nm.lib file RWN 04/18/2010 * library file for transistor parameters for TMSC 0.18 micron process * uses BIM parameters added 01/15/98 * can configure and attach to Nbreak and Pbreak transistors in PSpice **** ****************** 180nm TSMC parameters ************* *T14B SPICE BSIM3 VERSION 3.1 PARAMETERS * downloaded from MOSIS 04/18/10 *http://www.mosis.com/cgi-bin/cgiwrap/umosis/swp/params/ * tsmc-018/t92y_mm_non_epi_thk_mtl_params.txt *SPICE 3f5 Level 8, Star-HSPICE Level 49, UTMOST Level 8 * DATE: Jun 8/01 * LOT: T14B WAF: 06 * Temperature_parameters=Default *$ .MODEL TSMC180nmN NMOS ( LEVEL = 7 +VERSION = 3.1 TNOM = 27 TOX = 4.1E-9 +XJ = 1E-7 NCH = 2.3549E17 VTH0 = 0.354505 +K1 = 0.5733393 K2 = 3.177172E-3 K3 = 27.3563303 +K3B = -10 W0 = 2.341477E-5 NLX = 1.906617E-7 +DVT0W = 0 DVT1W = 0 DVT2W = 0 +DVT0 = 1.6751718 DVT1 = 0.4282625 DVT2 = 0.036004 +U0 = 327.3736992 UA = -4.52726E-11 UB = 4.46532E-19 +UC = -4.74051E-11 VSAT = 8.785346E4 A0 = 1.6897405 +AGS = 0.2908676 B0 = -8.224961E-9 B1 = -1E-7 +KETA = 0.021238 A1 = 8.00349E-4 A2 = 1 +RDSW = 105 PRWG = 0.5 PRWB = -0.2 +WR = 1 WINT = 0 LINT = 1.351737E-8 *+XL = -2E-8 XW = -1E-8 + DWG = 1.610448E-9 +DWB = -5.108595E-9 VOFF = -0.0652968 NFACTOR = 2.4901845 +CIT = 0 CDSC = 2.4E-4 CDSCD = 0 +CDSCB = 0 ETA0 = 0.0231564 ETAB = -0.058499 +DSUB = 0.9467118 PCLM = 0.8512348 PDIBLC1 = 0.0929526 +PDIBLC2 = 0.01 PDIBLCB = -0.1 DROUT = 0.5224026 +PSCBE1 = 7.979323E10 PSCBE2 = 1.522921E-9 PVAG = 0.01 +DELTA = 0.01 RSH = 6.8 MOBMOD = 1 +PRT = 0 UTE = -1.5 KT1 = -0.11 +KT1L = 0 KT2 = 0.022 UA1 = 4.31E-9 +UB1 = -7.61E-18 UC1 = -5.6E-11 AT = 3.3E4 +WL = 0 WLN = 1 WW = 0 +WWN = 1 WWL = 0 LL = 0 +LLN = 1 LW = 0 LWN = 1 +LWL = 0 CAPMOD = 2 XPART = 0.5 +CGDO = 7.7E-10 CGSO = 7.7E-10 CGBO = 1E-12 +CJ = 1.010083E-3 PB = 0.7344298 MJ = 0.3565066 +CJSW = 2.441707E-10 PBSW = 0.8005503 MJSW = 0.1327842 +CJSWG = 3.3E-10 PBSWG = 0.8005503 MJSWG = 0.1327842 +CF = 0 PVTH0 = 1.307195E-3 PRDSW = -5 +PK2 = -1.022757E-3 WKETA = -4.466285E-4 LKETA = -9.715157E-3 +PU0 = 12.2704847 PUA = 4.421816E-11 PUB = 0 +PVSAT = 1.707461E3 PETA0 = 1E-4 PKETA = 2.348777E-3 ) * *$ .MODEL TSMC180nmP PMOS ( LEVEL = 7 +VERSION = 3.1 TNOM = 27 TOX = 4.1E-9 +XJ = 1E-7 NCH = 4.1589E17 VTH0 = -0.4120614 +K1 = 0.5590154 K2 = 0.0353896 K3 = 0 +K3B = 7.3774572 W0 = 1E-6 NLX = 1.103367E-7 +DVT0W = 0 DVT1W = 0 DVT2W = 0 +DVT0 = 0.4301522 DVT1 = 0.2156888 DVT2 = 0.1 +U0 = 128.7704538 UA = 1.908676E-9 UB = 1.686179E-21 +UC = -9.31329E-11 VSAT = 1.658944E5 A0 = 1.6076505 +AGS = 0.3740519 B0 = 1.711294E-6 B1 = 4.946873E-6 +KETA = 0.0210951 A1 = 0.0244939 A2 = 1 +RDSW = 127.0442882 PRWG = 0.5 PRWB = -0.5 +WR = 1 WINT = 5.428484E-10 LINT = 2.468805E-8 *+XL = -2E-8 XW = -1E-8 +DWG = -2.453074E-8 +DWB = 6.408778E-9 VOFF = -0.0974174 NFACTOR = 1.9740447 +CIT = 0 CDSC = 2.4E-4 CDSCD = 0 +CDSCB = 0 ETA0 = 0.1847491 ETAB = -0.2531172 +DSUB = 1.5 PCLM = 4.8842961 PDIBLC1 = 0.0156227 +PDIBLC2 = 0.1 PDIBLCB = -1E-3 DROUT = 0 +PSCBE1 = 1.733878E9 PSCBE2 = 5.002842E-10 PVAG = 15 +DELTA = 0.01 RSH = 7.7 MOBMOD = 1 +PRT = 0 UTE = -1.5 KT1 = -0.11 +KT1L = 0 KT2 = 0.022 UA1 = 4.31E-9 +UB1 = -7.61E-18 UC1 = -5.6E-11 AT = 3.3E4 +WL = 0 WLN = 1 WW = 0 +WWN = 1 WWL = 0 LL = 0 +LLN = 1 LW = 0 LWN = 1 +LWL = 0 CAPMOD = 2 XPART = 0.5 +CGDO = 7.11E-10 CGSO = 7.11E-10 CGBO = 1E-12 +CJ = 1.179334E-3 PB = 0.8545261 MJ = 0.4117753 +CJSW = 2.215877E-10 PBSW = 0.6162997 MJSW = 0.2678074 +CJSWG = 4.22E-10 PBSWG = 0.6162997 MJSWG = 0.2678074 +CF = 0 PVTH0 = 2.283319E-3 PRDSW = 5.6431992 +PK2 = 2.813503E-3 WKETA = 2.438158E-3 LKETA = -0.0116078 +PU0 = -2.2514581 PUA = -7.62392E-11 PUB = 4.502298E-24 +PVSAT = -50 PETA0 = 1E-4 PKETA = -1.047892E-4 ) * *.ENDS *$ --- End code --- |
| Ian.M:
You've got the two traces mixed up. Add a cursor to the plot of V(out)/V(in) and you'll see that the phase starts at 180 deg at low frequencies (as it should be for an inverter) and starts decreasing at about 1MHz, crossing 90 deg at 64MHz and becoming close to 0 deg from about 1GHz upwards. Meanwhile the gain is about 7.5dB at low frequencies, increasing above 1MHz to 13.8dB at 64MHz and 20dB above 1GHz. I am perplexed by the increasing gain . . . |
| promach:
The increasing V(out)/V(in) gain magnitude is surprising. I have no idea why. Any idea why ? the V(out)/V(in) phase is due to V(in) and V(out) acted together. I have the following an updated AC plot : |
| iMo:
I can get some amplification out of it with different L and W and Vcc. The ac analysis shows crap. The dc sweep looks ok. It could be the spice models you have imported do not match the model levels in the LTspice. |
| MrAl:
--- Quote from: promach on January 29, 2019, 03:42:33 am ---I am having some issue interpreting the following AC phase plot. The AC gain plot is ok, rolling off at high frequencies, but what about the --- End quote --- which increases from 0 towards 180 degrees at higher frequencies ? Note: The current input stimulus and feedback resistor is configuring the inverter as a transimpedance amplifier. It’s to avoid disturbing the dc bias. test_cmos_inverter.asc --- Code: ---Version 4 SHEET 1 2264 2956 WIRE 256 -48 240 -48 WIRE 528 -48 256 -48 WIRE 240 0 240 -48 WIRE 256 48 256 -48 WIRE 256 48 240 48 WIRE 192 80 160 80 WIRE 160 160 160 80 WIRE 240 160 240 96 WIRE 240 192 240 160 WIRE 272 192 240 192 WIRE 384 192 272 192 WIRE 112 224 0 224 WIRE 160 224 160 160 WIRE 160 224 112 224 WIRE 240 224 240 192 WIRE 0 272 0 224 WIRE 256 272 240 272 WIRE 528 288 528 -48 WIRE 160 304 160 224 WIRE 192 304 160 304 WIRE 240 352 240 320 WIRE 256 352 256 272 WIRE 256 352 240 352 WIRE 0 416 0 352 WIRE 256 416 256 352 WIRE 256 416 0 416 WIRE 352 416 256 416 WIRE 384 416 384 272 WIRE 384 416 352 416 WIRE 528 416 528 368 WIRE 528 416 384 416 WIRE 352 448 352 416 FLAG 352 448 0 FLAG 112 224 in FLAG 272 192 out SYMBOL nmos4 192 224 R0 SYMATTR InstName M1 SYMATTR Value TSMC180nmN SYMATTR Value2 l=3u w=1.2u SYMBOL voltage 528 272 R0 SYMATTR InstName V1 SYMATTR Value 1.0 SYMBOL pmos4 192 0 R0 SYMATTR InstName M2 SYMATTR Value TSMC180nmP SYMATTR Value2 l=3u w=0.4u SYMBOL current 0 272 R0 WINDOW 123 24 102 Left 2 SYMATTR Value2 AC 1 SYMATTR InstName I1 SYMATTR Value 0 SYMBOL res 256 144 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 2 135 VTop 2 SYMATTR InstName R1 SYMATTR Value 1Meg SYMBOL current 384 192 R0 WINDOW 123 39 50 Left 2 WINDOW 3 68 23 Left 2 SYMATTR Value2 AC 0 SYMATTR InstName I2 SYMATTR Value 0 TEXT 864 176 Left 2 !.op TEXT 872 200 Left 2 !.ac dec 100 1 10g TEXT 816 328 Left 2 !.include tsmc180nmcmos.lib TEXT 808 256 Left 2 !;.dc I1 -165n 165n 1n --- End code --- tsmc180nmcmos.lib --- Code: ---* PSPICE TSMC180nm.lib file RWN 04/18/2010 * library file for transistor parameters for TMSC 0.18 micron process * uses BIM parameters added 01/15/98 * can configure and attach to Nbreak and Pbreak transistors in PSpice **** ****************** 180nm TSMC parameters ************* *T14B SPICE BSIM3 VERSION 3.1 PARAMETERS * downloaded from MOSIS 04/18/10 *http://www.mosis.com/cgi-bin/cgiwrap/umosis/swp/params/ * tsmc-018/t92y_mm_non_epi_thk_mtl_params.txt *SPICE 3f5 Level 8, Star-HSPICE Level 49, UTMOST Level 8 * DATE: Jun 8/01 * LOT: T14B WAF: 06 * Temperature_parameters=Default *$ .MODEL TSMC180nmN NMOS ( LEVEL = 7 +VERSION = 3.1 TNOM = 27 TOX = 4.1E-9 +XJ = 1E-7 NCH = 2.3549E17 VTH0 = 0.354505 +K1 = 0.5733393 K2 = 3.177172E-3 K3 = 27.3563303 +K3B = -10 W0 = 2.341477E-5 NLX = 1.906617E-7 +DVT0W = 0 DVT1W = 0 DVT2W = 0 +DVT0 = 1.6751718 DVT1 = 0.4282625 DVT2 = 0.036004 +U0 = 327.3736992 UA = -4.52726E-11 UB = 4.46532E-19 +UC = -4.74051E-11 VSAT = 8.785346E4 A0 = 1.6897405 +AGS = 0.2908676 B0 = -8.224961E-9 B1 = -1E-7 +KETA = 0.021238 A1 = 8.00349E-4 A2 = 1 +RDSW = 105 PRWG = 0.5 PRWB = -0.2 +WR = 1 WINT = 0 LINT = 1.351737E-8 *+XL = -2E-8 XW = -1E-8 + DWG = 1.610448E-9 +DWB = -5.108595E-9 VOFF = -0.0652968 NFACTOR = 2.4901845 +CIT = 0 CDSC = 2.4E-4 CDSCD = 0 +CDSCB = 0 ETA0 = 0.0231564 ETAB = -0.058499 +DSUB = 0.9467118 PCLM = 0.8512348 PDIBLC1 = 0.0929526 +PDIBLC2 = 0.01 PDIBLCB = -0.1 DROUT = 0.5224026 +PSCBE1 = 7.979323E10 PSCBE2 = 1.522921E-9 PVAG = 0.01 +DELTA = 0.01 RSH = 6.8 MOBMOD = 1 +PRT = 0 UTE = -1.5 KT1 = -0.11 +KT1L = 0 KT2 = 0.022 UA1 = 4.31E-9 +UB1 = -7.61E-18 UC1 = -5.6E-11 AT = 3.3E4 +WL = 0 WLN = 1 WW = 0 +WWN = 1 WWL = 0 LL = 0 +LLN = 1 LW = 0 LWN = 1 +LWL = 0 CAPMOD = 2 XPART = 0.5 +CGDO = 7.7E-10 CGSO = 7.7E-10 CGBO = 1E-12 +CJ = 1.010083E-3 PB = 0.7344298 MJ = 0.3565066 +CJSW = 2.441707E-10 PBSW = 0.8005503 MJSW = 0.1327842 +CJSWG = 3.3E-10 PBSWG = 0.8005503 MJSWG = 0.1327842 +CF = 0 PVTH0 = 1.307195E-3 PRDSW = -5 +PK2 = -1.022757E-3 WKETA = -4.466285E-4 LKETA = -9.715157E-3 +PU0 = 12.2704847 PUA = 4.421816E-11 PUB = 0 +PVSAT = 1.707461E3 PETA0 = 1E-4 PKETA = 2.348777E-3 ) * *$ .MODEL TSMC180nmP PMOS ( LEVEL = 7 +VERSION = 3.1 TNOM = 27 TOX = 4.1E-9 +XJ = 1E-7 NCH = 4.1589E17 VTH0 = -0.4120614 +K1 = 0.5590154 K2 = 0.0353896 K3 = 0 +K3B = 7.3774572 W0 = 1E-6 NLX = 1.103367E-7 +DVT0W = 0 DVT1W = 0 DVT2W = 0 +DVT0 = 0.4301522 DVT1 = 0.2156888 DVT2 = 0.1 +U0 = 128.7704538 UA = 1.908676E-9 UB = 1.686179E-21 +UC = -9.31329E-11 VSAT = 1.658944E5 A0 = 1.6076505 +AGS = 0.3740519 B0 = 1.711294E-6 B1 = 4.946873E-6 +KETA = 0.0210951 A1 = 0.0244939 A2 = 1 +RDSW = 127.0442882 PRWG = 0.5 PRWB = -0.5 +WR = 1 WINT = 5.428484E-10 LINT = 2.468805E-8 *+XL = -2E-8 XW = -1E-8 +DWG = -2.453074E-8 +DWB = 6.408778E-9 VOFF = -0.0974174 NFACTOR = 1.9740447 +CIT = 0 CDSC = 2.4E-4 CDSCD = 0 +CDSCB = 0 ETA0 = 0.1847491 ETAB = -0.2531172 +DSUB = 1.5 PCLM = 4.8842961 PDIBLC1 = 0.0156227 +PDIBLC2 = 0.1 PDIBLCB = -1E-3 DROUT = 0 +PSCBE1 = 1.733878E9 PSCBE2 = 5.002842E-10 PVAG = 15 +DELTA = 0.01 RSH = 7.7 MOBMOD = 1 +PRT = 0 UTE = -1.5 KT1 = -0.11 +KT1L = 0 KT2 = 0.022 UA1 = 4.31E-9 +UB1 = -7.61E-18 UC1 = -5.6E-11 AT = 3.3E4 +WL = 0 WLN = 1 WW = 0 +WWN = 1 WWL = 0 LL = 0 +LLN = 1 LW = 0 LWN = 1 +LWL = 0 CAPMOD = 2 XPART = 0.5 +CGDO = 7.11E-10 CGSO = 7.11E-10 CGBO = 1E-12 +CJ = 1.179334E-3 PB = 0.8545261 MJ = 0.4117753 +CJSW = 2.215877E-10 PBSW = 0.6162997 MJSW = 0.2678074 +CJSWG = 4.22E-10 PBSWG = 0.6162997 MJSWG = 0.2678074 +CF = 0 PVTH0 = 2.283319E-3 PRDSW = 5.6431992 +PK2 = 2.813503E-3 WKETA = 2.438158E-3 LKETA = -0.0116078 +PU0 = -2.2514581 PUA = -7.62392E-11 PUB = 4.502298E-24 +PVSAT = -50 PETA0 = 1E-4 PKETA = -1.047892E-4 ) * *.ENDS *$ --- End code --- --- End quote --- Hi, Why dont you have any load connected? You should probably connect some resistive load like maybe 1k or something. With no load you might be seeing the effects of parasitics. |
| Navigation |
| Message Index |
| Next page |