fast NPN in LT Spice

Define "fast".

2SC3838K looks OK.

That doesn't seem to be in the LT Spice library.

It's hard to pick parts, discrete or ICs, from the library.

It isn't but models are easy to find, make sure the link I posted includes the end quote.

I've never done any ECL modeling but

Yes it would be nice if a description of the part as well as the part number could be included.

A sortable column of Ft would be nice for transistors. Lacking that, sorting on Vce helps spot the RF parts. Low voltage suggests RF.

Here's a circuit that includes a 5GHz ft BFR92A, which a typical broad-band transistor. I had to put in the Spice model into the .asc file myself. There used to be quite a few of them around, but - as Phil Hobbs has mentioned - most of them have gone obsolete. He has tracked down a surviving PNP equivalent, but you won't need that to simulate ECL.

It's not the first time I've posted such a .asc file here.

Version 4 SHEET 1 2924 1040 WIRE 128 -720 -768 -720 WIRE 304 -720 128 -720 WIRE 656 -720 304 -720 WIRE 1088 -720 656 -720 WIRE 1376 -720 1088 -720 WIRE 1584 -720 1376 -720 WIRE 1088 -576 1088 -720 WIRE 1376 -576 1376 -720 WIRE 128 -560 128 -720 WIRE 304 -560 304 -720 WIRE 656 -560 656 -720 WIRE 1584 -544 1584 -720 WIRE 1088 -400 1088 -496 WIRE 1088 -400 960 -400 WIRE 1248 -400 1088 -400 WIRE 960 -368 960 -400 WIRE 1248 -352 1248 -400 WIRE 656 -320 656 -480 WIRE 896 -320 656 -320 WIRE 1376 -304 1376 -496 WIRE 1376 -304 1312 -304 WIRE 128 -288 128 -480 WIRE 176 -288 128 -288 WIRE 304 -288 304 -480 WIRE 304 -288 240 -288 WIRE 656 -208 656 -320 WIRE 1376 -192 1376 -304 WIRE 1584 -192 1584 -480 WIRE 1584 -192 1376 -192 WIRE 304 -160 304 -288 WIRE 448 -160 304 -160 WIRE 592 -160 448 -160 WIRE -768 -64 -768 -720 WIRE 128 48 128 -288 WIRE 1376 48 1376 -192 WIRE -272 96 -432 96 WIRE 64 96 -192 96 WIRE 304 160 304 -160 WIRE 448 176 448 -160 WIRE -432 240 -432 96 WIRE -768 416 -768 16 WIRE -768 416 -880 416 WIRE -736 416 -768 416 WIRE -432 416 -432 320 WIRE -432 416 -736 416 WIRE 304 416 304 240 WIRE 304 416 -432 416 WIRE 960 416 960 -272 WIRE 960 416 304 416 WIRE 1376 416 1376 128 WIRE 1376 416 960 416 WIRE 1424 416 1376 416 WIRE 1520 416 1424 416 WIRE 128 464 128 144 WIRE 656 464 656 -112 WIRE 656 464 128 464 WIRE 1424 480 1424 416 WIRE -880 496 -880 416 WIRE 656 496 656 464 WIRE 1248 624 1248 -256 WIRE 1296 624 1248 624 WIRE 1424 624 1424 560 WIRE 1424 624 1296 624 WIRE -736 640 -736 416 WIRE -736 656 -736 640 WIRE 1424 688 1424 624 WIRE -736 944 -736 720 WIRE 448 944 448 256 WIRE 448 944 -736 944 WIRE 656 944 656 576 WIRE 656 944 448 944 WIRE 1424 944 1424 768 WIRE 1424 944 656 944 WIRE 1648 944 1424 944 FLAG -880 496 0 FLAG 1296 624 out SYMBOL npn 64 48 R0 SYMATTR InstName Q1 SYMATTR Value BFR92A SYMBOL npn 592 -208 R0 SYMATTR InstName Q2 SYMATTR Value BFR92A SYMBOL voltage -768 -80 R0 WINDOW 123 0 0 Left 0 WINDOW 39 24 44 Left 2 SYMATTR SpiceLine Rser=0.1 SYMATTR InstName V1 SYMATTR Value 15.0 SYMBOL voltage -736 624 R0 WINDOW 123 0 0 Left 0 WINDOW 39 24 44 Left 2 SYMATTR SpiceLine Rser=0.1 SYMATTR InstName V2 SYMATTR Value 15.0 SYMBOL voltage -432 224 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V3 SYMATTR Value PULSE(0 .2 1n 300p 300p 100p 100n 2) SYMBOL res -176 80 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R1 SYMATTR Value 27 SYMBOL res 640 480 R0 SYMATTR InstName R3 SYMATTR Value 3k0 SYMBOL res 112 -576 R0 SYMATTR InstName R4 SYMATTR Value 2k SYMBOL res 288 144 R0 SYMATTR InstName R5 SYMATTR Value 100 SYMBOL res 640 -576 R0 SYMATTR InstName R6 SYMATTR Value 1k SYMBOL res 288 -576 R0 SYMATTR InstName R2 SYMATTR Value 5k SYMBOL cap 240 -304 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C1 SYMATTR Value 10p SYMBOL res 432 160 R0 SYMATTR InstName R7 SYMATTR Value 7k5 SYMBOL pnp 1312 -256 R180 SYMATTR InstName Q3 SYMATTR Value 2N3906 SYMBOL pnp 896 -272 M180 SYMATTR InstName Q4 SYMATTR Value 2N3906 SYMBOL res 1072 -592 R0 SYMATTR InstName R8 SYMATTR Value 100 SYMBOL res 1360 -592 R0 SYMATTR InstName R9 SYMATTR Value 3k3 SYMBOL res 1360 32 R0 SYMATTR InstName R10 SYMATTR Value 12k SYMBOL res 1408 464 R0 SYMATTR InstName R11 SYMATTR Value 56 SYMBOL res 1408 672 R0 SYMATTR InstName R12 SYMATTR Value 360 SYMBOL cap 1568 -544 R0 SYMATTR InstName C2 SYMATTR Value 10n TEXT -272 1000 Left 2 !.model BFR92A NPN(IS=0.1213E-15 VAF=30 BF=94.73 IKF=0.46227 XTB=0 BR=10.729 CJC=946.47E-15 CJE=10.416E-15 TR=1.2744E-9 TF=26.796E-12 ITF=0.0044601 VTF=0.32861 XTF=0.3817 RB=14.998 RC=0.13793 RE=0.29088 Vceo=15 Icrating=4m mfg=Infineon) TEXT -904 1024 Left 2 !.tran 0 300n 0

Ft isn’t one of the model parameters, guess you have to look for low Tf and Tr transit times or low junction capacitances?

I always used the -now obsolete- BFR92A for such things. That's a 5GHz Ft NPN that I used often. It's not in the library, I think. Below the model. Mind the line wraps.

Jeroen Belleman

.model BFR92A NPN IS=4.11877E-016 BF=1.02639E+002 NF=9.97275E-001 VAF=6.26719E+001 IKF=3.20054E+000 ISE=4.01062E-015 NE=1.57708E+000 BR=1.81086E+001 NR=9.96202E-001 VAR=3.36915E+000 IKR=1.28155E+000 ISC=2.79905E-016 NC=1.07543E+000 RB=1.00000E+001 IRB=1.00000E-006 RBM=1.00000E+001 RE=1.16450E+000 RC=2.32000E+000 EG=1.11000E+000 XTI=3.00000E+000 CJE=8.90512E-013 VJE=6.00000E-001 MJE=2.58570E-001 TF=1.54973E-011 XTF=3.91402E+001 VTF=2.15279E+000 ITF=2.13776E-001 CJC=5.46563E-013 VJC=3.80824E-001 MJC=2.02935E-001

From the standard.bjt spice parameter spreadsheet, compiled some time ago, there are a few ecl spice models.

.MODEL ECLTN04P75 NPN(IS=6.50E-18 ISE=3.40E-16 ISC=0 ISS=0.0 XTI=4 BF=120 BR=10 IKF=8.0E-3 IKR=7E-4 XTB=0.73 VAF=30 VAR=5 VJE=0.9 VJC=0.67 VJS=0.75 RE=17.5 RB=378.5 RC=74 RBM=120 CJE=2.36E=14 CJS=5.38E-14 CJC=2.74E-14 XCJC=.3 FC=0.9 NF=1 NR=1 NE=2 NC=2 NS=1.0 MJE=0.4 MJC=0.32 MJS=0.4 TF=8E-12 TR=1E-9 Trb1=0 Tre1=0.0 Trc1=0.0 TRM1=0.0 IRB=1E-5 ITF=2.1E-2 VTF=1.4 XTF=10 GAMMA=1E-11 Rco=0 Nk=0.5 PTF=0 EG=1.1 KF=0 AF=1 Qco=0 Vo=10 Quasimod=0 IBVbe=1E-10 Bvbe=1E5 BVcbo=1E5 Vceo=5.5 Icrating=0 MFG=1.74u_x_4.75u_emitter) .MODEL ECLTN06 NPN(IS=8.56E-18 ISE=4.48E-16 ISC=0 ISS=0.0 XTI=4 BF=120 BR=10 IKF=1.05E-2 IKR=9.22E-4 XTB=0.73 VAF=30 VAR=5 VJE=0.9 VJC=0.67 VJS=0.75 RE=13.3 RB=291.4 RC=62.7 RBM=95 CJE=2.99E-14 CJS=6.09E-14 CJC=3.12E-14 XCJC=.3 FC=0.9 NF=1 NR=1 NE=2 NC=2 NS=1.0 MJE=0.4 MJC=0.32 MJS=0.4 TF=8E-12 TR=1E-9 Trb1=0 Tre1=0.0 Trc1=0.0 TRM1=0.0 IRB=1.32E-5 ITF=2.76E-2 VTF=1.4 XTF=10 GAMMA=1E-11 Rco=0 Nk=0.5 PTF=0 EG=1.1 KF=0 AF=1 Qco=0 Vo=10 Quasimod=0 IBVbe=1E-10 Bvbe=1E5 BVcbo=1E5 Vceo=5.5 Icrating=0 MFG=1.75u_x_6.0u_emitter)

.MODEL ECLTN13P5 NPN(IS=2.09E-17 ISE=1.09E-15 ISC=0 ISS=0.0 XTI=4 BF=120 BR=10 IKF=2.57E-2 IKR=2.25E-3 XTB=0.73 VAF=30 VAR=5 VJE=0.9 VJC=0.67 VJS=0.75 RE=5.44 RB=122.6 RC=32.8 RBM=42.2 CJE=6.74E-14 CJS=1.03E-13 CJC=5.38E-14 XCJC=.3 FC=0.9 NF=1 NR=1 NE=2 NC=2 NS=1.0 MJE=0.4 MJC=0.32 MJS=0.4 TF=8E-12 TR=1E-9 Trb1=0 Tre1=0.0 Trc1=0.0 TRM1=0.0 IRB=3.22E-5 ITF=6.75E-2 VTF=1.4 XTF=10 GAMMA=1E-11 Rco=0 Nk=0.5 PTF=0 EG=1.1 KF=0 AF=1 Qco=0 Vo=10 Quasimod=0 IBVbe=1E-10 Bvbe=1E5 BVcbo=1E5 Vceo=5.5 Icrating=0 MFG=1.75u_x_13.5u_emitter)

.MODEL ECLTN4 NPN(IS=5.27E-18 ISE=2.75E-16 ISC=0 ISS=0.0 XTI=4 BF=120 BR=10 IKF=6.48E-3 IKR=5.67E-4 XTB=0.73 VAF=30 VAR=5 VJE=0.9 VJC=0.67 VJS=0.75 RE=21.6 RB=461.6 RC=83.1 RBM=142.5 CJE=19.9E-15 CJS=49.6E-15 CJC=25.1E-15 XCJC=0.3 FC=0.9 NF=1 NR=1 NE=2 NC=2 NS=1.0 MJE=0.4 MJC=0.32 MJS=0.4 TF=8E-12 TR=1E-9 Trb1=0 Tre1=0.0 Trc1=0.0 TRM1=0.0 IRB=8.1E-6 ITF=1.7E-2 VTF=1.4 XTF=10 GAMMA=1E-11 Rco=0 Nk=0.5 PTF=0 EG=1.1 KF=0 AF=1 Qco=0 Vo=10 Quasimod=0 IBVbe=1E-10 Bvbe=1E5 BVcbo=1E5 Vceo=5.5 Icrating=0 MFG=1.75u_x_4.0u_emitter) .MODEL ECLTNECLIPS NPN(IS=2.27E-16 ISE=1.19E-14 ISC=0 ISS=0.0 XTI=4 BF=120 BR=10 IKF=0.279 IKR=2.44E-2 XTB=0.73 VAF=30 VAR=5 VJE=0.9 VJC=0.67 VJS=0.75 RE=0.501 RB=15.98 RC=11.1 RBM=4.17 CJE=6.11E-13 CJS=6.68E-13 CJC=4.4E-13 XCJC=.3 FC=0.9 NF=1 NR=1 NE=2 NC=2 NS=1.0 MJE=0.4 MJC=0.32 MJS=0.4 TF=8E-12 TR=1E-9 Trb1=0 Tre1=0.0 Trc1=0.0 TRM1=0.0 IRB=3.49E-4 ITF=0.733 VTF=1.4 XTF=10 GAMMA=1E-11 Rco=0 Nk=0.5 PTF=0 EG=1.1 KF=0 AF=1 Qco=0 Vo=10 Quasimod=0 IBVbe=1E-10 Bvbe=1E5 BVcbo=1E5 Vceo=5.5 Icrating=0 MFG=ECLout)

This is a simple text copy/paste into notepad, with tabs removed and carriage returns added.

RL

Gosh, what a hideous mess, in many respects.

Agreed, but reading hundreds of lines of fine print, or looking up hundreds of data sheets, is a nuisance.

I sorted on lowest Vce and then found the capacitances and then looked up the data sheets. LT Spice is not friendly to people with bad vision.

I should have used one of the LS3xx parts. They have Vceo and Ic both = 0.

Do tell us why. You do claim to revel in electronic discussion.

On Mon, 3 Jun 2024 09:58:52 +0200, Jeroen Belleman snipped-for-privacy@nospam.please wrote:

This is actually a bit faster than the MC10EP89:

Version 4 SHEET 1 1208 700 WIRE 112 -64 -16 -64 WIRE 272 -64 112 -64 WIRE 400 -64 272 -64 WIRE 576 -64 400 -64 WIRE 576 0 576 -64 WIRE -16 16 -16 -64 WIRE 272 16 272 -64 WIRE 400 96 400 -64 WIRE 272 144 272 96 WIRE 336 144 272 144 WIRE 576 144 576 80 WIRE -192 192 -368 192 WIRE -128 192 -192 192 WIRE -128 224 -128 192 WIRE 112 224 112 -64 WIRE -368 240 -368 192 WIRE 400 256 400 192 WIRE 576 256 400 256 WIRE 624 256 576 256 WIRE 640 256 624 256 WIRE -16 272 -16 96 WIRE 48 272 -16 272 WIRE -368 352 -368 320 WIRE -192 352 -368 352 WIRE -128 352 -128 304 WIRE -128 352 -192 352 WIRE 112 384 112 320 WIRE 400 384 112 384 WIRE 624 384 400 384 WIRE 640 384 624 384 WIRE -368 400 -368 352 WIRE -16 432 -16 272 WIRE 272 432 272 144 WIRE 400 432 400 384 WIRE 576 432 576 256 WIRE -16 560 -16 512 WIRE 272 560 272 512 WIRE 400 560 400 512 WIRE 576 560 576 512 FLAG 576 144 0 FLAG -192 192 A FLAG -192 352 B FLAG 624 256 X FLAG 624 384 Y FLAG -16 560 0 FLAG 272 560 0 FLAG -368 400 0 FLAG 400 560 0 FLAG 576 560 0 SYMBOL npn 336 96 R0 WINDOW 0 100 21 Left 2 WINDOW 3 71 55 Left 2 SYMATTR InstName Q1 SYMATTR Value 2SC3838K SYMBOL voltage 576 -16 R0 WINDOW 0 48 40 Left 2 WINDOW 3 54 75 Left 2 SYMATTR InstName V1 SYMATTR Value 5 SYMBOL res 256 0 R0 WINDOW 0 -65 38 Left 2 WINDOW 3 -70 76 Left 2 SYMATTR InstName R2 SYMATTR Value 200 SYMBOL npn 48 224 R0 WINDOW 0 100 21 Left 2 WINDOW 3 71 55 Left 2 SYMATTR InstName Q2 SYMATTR Value 2SC3838K SYMBOL res -32 0 R0 WINDOW 0 53 46 Left 2 WINDOW 3 48 80 Left 2 SYMATTR InstName R1 SYMATTR Value 200 SYMBOL bi -16 432 R0 WINDOW 0 58 111 Left 2 WINDOW 3 -343 170 Left 2 SYMATTR InstName B1 SYMATTR Value I=4m*( 1 - tanh (200 * ( V(B)-V(A) ) ) ) SYMBOL res -144 208 R0 WINDOW 0 -60 48 Left 2 WINDOW 3 -69 79 Left 2 SYMATTR InstName R5 SYMATTR Value 10K SYMBOL bi 272 432 R0 WINDOW 0 -91 109 Left 2 WINDOW 3 -100 169 Left 2 SYMATTR InstName B2 SYMATTR Value I=4m*( 1 - tanh (200 * ( V(A)-V(B) ) ) ) SYMBOL voltage -368 224 R0 WINDOW 0 -58 -21 Left 2 WINDOW 3 -94 -80 Left 2 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V2 SYMATTR Value PULSE(-1 1 1n 500p 500p 2n) SYMBOL res 384 416 R0 WINDOW 0 53 40 Left 2 WINDOW 3 47 71 Left 2 SYMATTR InstName R3 SYMATTR Value 200 SYMBOL res 560 416 R0 WINDOW 0 49 36 Left 2 WINDOW 3 46 71 Left 2 SYMATTR InstName R4 SYMATTR Value 200 TEXT -288 48 Left 2 !.tran 5n TEXT 416 232 Left 2 ;1.6v pp TEXT -296 -40 Left 2 ;MC10EP89 TEXT 136 360 Left 2 ;1.6v pp TEXT -328 0 Left 2 ;JL Jun 2 2024

Or you can look at wide-band transistors, pick one and plug the manufacturers Spice model into LTSpice yourself, which is something I've done from time to time (and posted the .asc files here), and John Larkin doesn't seem to be able to manage.

He's just described the example I pulled out of the circuit file on my computer as "hideous mess", which is inaccurate. Nobody would use +/-15V rails to drive just that circuit, but if +/-15V rails are what you have got, that circuit could solve a specific problem.

Looking at what distributors offer is easier and quicker.

They have an interest in offering their various customer the parts they are likely to buy. Mouser did let me pick out the BFR92A pretty quickly.

LTSpice is in the business of modelling the parts you select, not selecting them for you

It is worth noting that even 3.5GHz transistors tend to need base-stopper resistors in real life. Collector-base capacitive feedback can make them self-oscillate without it. Phil Hobbs has found two Murata ferrite bead/chips which are specified as presenting resistive impedances of 60R and 200R at 5GHz which seems to do the job too.

Jim Thompson designed that kind of integrated circuit, but he's been dead for a while now.

Tr and Tf are useful for models.

There are a few more ecl models in the current spreadsheet. Some are duplicates from different revs or sources - variations possibly due to published typos. (~ varying XTI, VJS, IKF, ITF)