LDO transient performance enhancement circuit understanding - Page 1
Forum section: electronics / projects

author: promach
author_rank: Frequent Contributor
timestamp: February 28, 2020, 02:32:20 pm
content: For the following LDO circuit, how does the transient performance enhancement circuit sub-block in green color works ?

author: promach
author_rank: Frequent Contributor
timestamp: February 29, 2020, 02:25:08 am
content: For this LDO circuit , I have pretty good transient output voltage V(vout) for a 100k sine input on Vin.But it goes very bad when I use 1MEG sine input on Vin.Any advice ?LDO.ascCode:Version 4SHEET 1 3764 1620WIRE -416 80 -512 80WIRE -272 80 -416 80WIRE -208 80 -272 80WIRE 96 80 -208 80WIRE 144 80 96 80WIRE 1216 80 144 80WIRE 2064 80 1216 80WIRE 2320 80 2064 80WIRE 2384 80 2320 80WIRE 2784 80 2384 80WIRE 2848 80 2784 80WIRE 3152 80 2848 80WIRE 3216 80 3152 80WIRE 3472 80 3216 80WIRE 3536 80 3472 80WIRE -208 128 -208 80WIRE 96 128 96 80WIRE 2384 128 2384 80WIRE 2784 128 2784 80WIRE 3152 128 3152 80WIRE 3472 128 3472 80WIRE 2064 144 2064 80WIRE 2064 144 2016 144WIRE 2016 160 2016 144WIRE -272 176 -272 80WIRE -208 176 -272 176WIRE 144 176 144 80WIRE 144 176 96 176WIRE 2320 176 2320 80WIRE 2384 176 2320 176WIRE 2848 176 2848 80WIRE 2848 176 2784 176WIRE 3216 176 3216 80WIRE 3216 176 3152 176WIRE 3536 176 3536 80WIRE 3536 176 3472 176WIRE -80 208 -160 208WIRE -16 208 -80 208WIRE 48 208 -16 208WIRE 2064 208 2064 144WIRE 2064 208 2016 208WIRE 2640 208 2432 208WIRE 2736 208 2640 208WIRE 3104 208 3056 208WIRE 3424 208 3392 208WIRE -16 240 -16 208WIRE 1968 240 -16 240WIRE -512 272 -512 80WIRE 2640 304 2640 208WIRE 2784 304 2784 224WIRE 2784 304 2640 304WIRE 2016 320 2016 256WIRE 2384 320 2384 224WIRE 2384 320 2016 320WIRE 3056 320 3056 208WIRE 3056 320 2384 320WIRE 3392 320 3392 208WIRE 3392 320 3056 320WIRE -208 336 -208 224WIRE -80 336 -80 208WIRE -80 336 -208 336WIRE 496 368 448 368WIRE 1040 368 496 368WIRE 1216 368 1216 80WIRE 1216 368 1040 368WIRE 1536 368 1216 368WIRE 1584 368 1536 368WIRE 496 384 496 368WIRE 1536 384 1536 368WIRE -512 432 -512 352WIRE 448 432 448 368WIRE 496 432 448 432WIRE 1584 432 1584 368WIRE 1584 432 1536 432WIRE 640 464 544 464WIRE 1488 464 640 464WIRE 2432 560 2368 560WIRE 496 592 496 480WIRE 640 592 640 464WIRE 640 592 496 592WIRE 2320 608 1840 608WIRE 2368 608 2368 560WIRE 2432 608 2432 560WIRE 2432 608 2416 608WIRE 2672 608 2432 608WIRE 3392 608 3392 320WIRE 3392 608 2672 608WIRE 1040 624 1040 368WIRE 1040 624 992 624WIRE 992 640 992 624WIRE 1840 640 1840 608WIRE 2016 672 2016 320WIRE 2064 672 2016 672WIRE 1040 688 1040 624WIRE 1040 688 992 688WIRE 2016 688 2016 672WIRE 2560 704 2512 704WIRE 2672 704 2672 608WIRE 2672 704 2560 704WIRE 3472 704 3472 224WIRE 3536 704 3472 704WIRE -208 720 -208 336WIRE 944 720 -208 720WIRE 2512 720 2512 704WIRE 2064 736 2064 672WIRE 2064 736 2016 736WIRE 1536 768 1536 480WIRE 1840 768 1840 704WIRE 1840 768 1536 768WIRE 1968 768 1840 768WIRE 2560 768 2560 704WIRE 2560 768 2512 768WIRE 2336 800 2336 656WIRE 2464 800 2336 800WIRE 96 832 96 224WIRE 96 832 -64 832WIRE 848 880 800 880WIRE 992 880 992 736WIRE 992 880 848 880WIRE 1184 880 992 880WIRE 1232 880 1184 880WIRE 2336 880 2336 800WIRE 2512 880 2512 816WIRE 2512 880 2336 880WIRE -208 896 -208 720WIRE 96 896 96 832WIRE 800 896 800 880WIRE 1232 896 1232 880WIRE 1872 928 1760 928WIRE 3392 928 3392 608WIRE 3392 928 1936 928WIRE -208 944 -272 944WIRE 160 944 96 944WIRE 848 944 848 880WIRE 848 944 800 944WIRE 1184 944 1184 880WIRE 1184 944 848 944WIRE 1232 944 1184 944WIRE -64 976 -64 832WIRE -64 976 -160 976WIRE 48 976 -64 976WIRE 704 976 688 976WIRE 752 976 704 976WIRE 1664 976 1280 976WIRE 2992 976 2640 976WIRE 3152 976 3152 224WIRE 3152 976 2992 976WIRE 688 1008 688 976WIRE 3472 1008 3472 704WIRE 2512 1040 2512 880WIRE 2784 1040 2784 304WIRE 3152 1040 3152 976WIRE 2512 1088 2448 1088WIRE 2784 1088 2720 1088WIRE 3216 1088 3152 1088WIRE 2640 1120 2640 976WIRE 2640 1120 2560 1120WIRE 2992 1120 2992 976WIRE 2992 1120 2832 1120WIRE 3104 1120 2992 1120WIRE 96 1136 96 992WIRE 96 1136 -64 1136WIRE 688 1136 688 1088WIRE 800 1168 800 992WIRE 800 1168 640 1168WIRE 1232 1168 1232 992WIRE 1376 1168 1232 1168WIRE -208 1200 -208 992WIRE 96 1200 96 1136WIRE 496 1232 496 592WIRE 800 1232 800 1168WIRE 1232 1232 1232 1168WIRE 1536 1232 1536 768WIRE -208 1248 -272 1248WIRE 160 1248 96 1248WIRE 1664 1264 1664 976WIRE 3360 1264 1664 1264WIRE 3472 1264 3472 1088WIRE 3472 1264 3360 1264WIRE -64 1280 -64 1136WIRE -64 1280 -160 1280WIRE 48 1280 -64 1280WIRE 496 1280 432 1280WIRE 864 1280 800 1280WIRE 1232 1280 1168 1280WIRE 1600 1280 1536 1280WIRE 640 1312 640 1168WIRE 640 1312 544 1312WIRE 672 1312 640 1312WIRE 752 1312 672 1312WIRE 1376 1312 1376 1168WIRE 1376 1312 1280 1312WIRE 1488 1312 1376 1312WIRE -208 1376 -208 1296WIRE 3472 1392 3472 1264WIRE 496 1424 496 1328WIRE 800 1424 800 1328WIRE 800 1424 496 1424WIRE 1008 1424 800 1424WIRE 1232 1424 1232 1328WIRE 1232 1424 1008 1424WIRE 1536 1424 1536 1328WIRE 1536 1424 1232 1424WIRE 1008 1472 1008 1424WIRE -208 1520 -208 1456WIRE -64 1520 -208 1520WIRE 96 1520 96 1296WIRE 96 1520 -64 1520WIRE 672 1536 672 1312WIRE 1760 1536 1760 928WIRE 1760 1536 672 1536WIRE 2016 1536 2016 784WIRE 2512 1536 2512 1136WIRE 2512 1536 2016 1536WIRE 2784 1536 2784 1136WIRE 2784 1536 2512 1536WIRE 3152 1536 3152 1136WIRE 3152 1536 2784 1536WIRE 3472 1536 3472 1472WIRE 3472 1536 3152 1536WIRE -64 1568 -64 1520WIRE 3472 1568 3472 1536FLAG 432 1280 0FLAG 864 1280 0FLAG 1168 1280 0FLAG 1600 1280 0FLAG 1008 1472 0FLAG -512 432 0FLAG 3472 1568 0FLAG 3216 1088 0FLAG 2720 1088 0FLAG 2448 1088 0FLAG 3536 704 VoutIOPIN 3536 704 OutFLAG 688 1136 0FLAG 704 976 VrefFLAG -416 80 VinFLAG 3360 1264 VfbFLAG -272 1248 0FLAG 160 1248 0FLAG -64 1568 0FLAG -272 944 0FLAG 160 944 0SYMBOL pmos4 48 128 R0WINDOW 123 62 94 Left 2SYMATTR Value2 L=0.18u W=6u m=2SYMATTR InstName M2SYMATTR Value PMSYMBOL pmos4 1488 384 R0WINDOW 123 56 100 Left 2SYMATTR Value2 L=0.18u W=6u m=4SYMATTR InstName M7SYMATTR Value PMSYMBOL pmos4 544 384 M0WINDOW 123 -11 101 Left 2SYMATTR Value2 L=0.18u W=6u m=4SYMATTR InstName M8SYMATTR Value PMSYMBOL pmos4 1968 160 R0WINDOW 123 56 100 Left 2SYMATTR Value2 L=0.18u W=6u m=2SYMATTR InstName M9SYMATTR Value PMSYMBOL pmos4 944 640 R0WINDOW 123 56 100 Left 2SYMATTR Value2 L=0.18u W=6u m=4SYMATTR InstName M10SYMATTR Value PMSYMBOL nmos4 544 1232 M0WINDOW 123 56 100 Left 2SYMATTR Value2 L=0.18u W=6u m=8SYMATTR InstName M11SYMATTR Value NMSYMBOL nmos4 752 1232 R0WINDOW 123 -43 119 Left 2SYMATTR Value2 L=0.18u W=6u m=2SYMATTR InstName M12SYMATTR Value NMSYMBOL pmos4 1280 896 M0WINDOW 0 43 30 Left 2WINDOW 123 56 100 Left 2SYMATTR InstName M13SYMATTR Value2 L=0.18u W=6u m=4SYMATTR Value PMSYMBOL pmos4 752 896 R0WINDOW 0 43 30 Left 2WINDOW 123 56 100 Left 2SYMATTR InstName M15SYMATTR Value2 L=0.18u W=6u m=4SYMATTR Value PMSYMBOL nmos4 1280 1232 M0WINDOW 123 56 100 Left 2SYMATTR Value2 L=0.18u W=6u m=2SYMATTR InstName M16SYMATTR Value NMSYMBOL nmos4 1488 1232 R0WINDOW 123 -39 112 Left 2SYMATTR Value2 L=0.18u W=6u m=8SYMATTR InstName M17SYMATTR Value NMSYMBOL voltage -512 256 R0WINDOW 123 24 124 Left 2WINDOW 39 0 0 Left 0SYMATTR Value2 AC 1SYMATTR InstName VinSYMATTR Value SINE(3.3 1 1MEG)SYMBOL cap 1936 912 R90WINDOW 0 0 32 VBottom 2WINDOW 3 32 32 VTop 2SYMATTR InstName C1SYMATTR Value 1pSYMBOL res 3456 992 R0SYMATTR InstName R1SYMATTR Value 10kSYMBOL res 3456 1376 R0SYMATTR InstName R2SYMATTR Value 10kSYMBOL pmos4 1968 688 R0WINDOW 123 56 100 Left 2SYMATTR Value2 L=0.18u W=6u m=8SYMATTR InstName M18SYMATTR Value PMSYMBOL cap 1824 640 R0SYMATTR InstName C2SYMATTR Value 1pSYMBOL pmos4 2432 128 M0WINDOW 123 -77 116 Left 2SYMATTR Value2 L=0.18u W=6u m=8SYMATTR InstName M19SYMATTR Value PMSYMBOL pmos4 3424 128 R0WINDOW 123 56 100 Left 2SYMATTR Value2 L=0.18u W=6u m=2000SYMATTR InstName M20SYMATTR Value PMSYMBOL pmos4 2416 656 M270WINDOW 123 56 100 Left 2SYMATTR Value2 L=0.18u W=6u m=1SYMATTR InstName M22SYMATTR Value PMSYMBOL pmos4 2464 720 R0WINDOW 123 56 100 Left 2SYMATTR Value2 L=0.18u W=6u m=1SYMATTR InstName M21SYMATTR Value PMSYMBOL pmos4 3104 128 R0WINDOW 123 56 100 Left 2SYMATTR Value2 L=0.18u W=6u m=8SYMATTR InstName M23SYMATTR Value PMSYMBOL nmos4 3104 1040 R0WINDOW 123 56 100 Left 2SYMATTR Value2 L=0.18u W=6u m=8SYMATTR InstName M24SYMATTR Value NMSYMBOL nmos4 2832 1040 M0WINDOW 123 -77 114 Left 2SYMATTR Value2 L=0.18u W=6u m=2SYMATTR InstName M25SYMATTR Value NMSYMBOL nmos4 2560 1040 M0WINDOW 123 -77 114 Left 2SYMATTR Value2 L=0.18u W=6u m=2SYMATTR InstName M26SYMATTR Value NMSYMBOL pmos4 2736 128 R0WINDOW 123 56 100 Left 2SYMATTR Value2 L=0.18u W=6u m=2SYMATTR InstName M27SYMATTR Value PMSYMBOL voltage 688 992 M0SYMATTR InstName VrefSYMATTR Value DC 1.1VSYMBOL nmos4 -160 1200 M0WINDOW 123 56 100 Left 2SYMATTR Value2 L=0.18u W=6u m=2SYMATTR InstName M1SYMATTR Value NMSYMBOL nmos4 48 1200 R0WINDOW 123 -43 119 Left 2SYMATTR Value2 L=0.18u W=6u m=2SYMATTR InstName M3SYMATTR Value NMSYMBOL nmos4 -160 896 M0WINDOW 123 56 100 Left 2SYMATTR Value2 L=0.18u W=6u m=2SYMATTR InstName M4SYMATTR Value NMSYMBOL nmos4 48 896 R0WINDOW 123 -43 119 Left 2SYMATTR Value2 L=0.18u W=6u m=2SYMATTR InstName M5SYMATTR Value NMSYMBOL pmos4 -160 128 M0WINDOW 123 -77 116 Left 2SYMATTR Value2 L=0.18u W=6u m=1SYMATTR InstName M6SYMATTR Value PMSYMBOL res -192 1360 M0SYMATTR InstName R3SYMATTR Value 22kTEXT 64 32 Left 2 !.lib mosfet_018.libTEXT 344 32 Left 2 !.tran 100uTEXT 520 32 Left 2 !;.ac dec 100 1 1g

author: promach
author_rank: Frequent Contributor
timestamp: March 27, 2020, 02:38:18 pm
content: Why does the transient simulation around 10us have a lot of noise ?Where is the actualroot causefor such deterministic noise at 10us after simulation starts ? And any idea how to eliminate it entirely from the noise source ?