Why is there no dual gate fets in LTspice?

Just set the inductances. L goes up as turns squared.

Use the "K" thing to set the coupling/leakage inductance.

You get the SiGe:C's effectively infinite Early voltage, lower C_dg, and very low C_out. That means you can run higher gain.

Cheers

Phil Hobbs

Most are gone. NXP has some low noise dg fets. They are probably easier to use at UHF/ VHF than a hot 10+GHz XXXfet.

Apologies to OP, seemed to have hijacked your thread, but please bear with us here...

You missed the syntax of K1 and the ease of plotting BH Curve.

Although I laud LTspice for using MKS units it can get confusing, going back and forth...

Hc = 1.251 Oe = 99.55 A/m Bs = 1.202e3 G = .1202 T Br = 85.14 G = .008514 T Area = 3.27156 = 327.156e-6 sq m Path = 12.90399 = .129039 m Gap = 0 = 0 ??

B from Gauss to Tesla divide by 1e4 H from Oersted to Amp/m multiply by 79.57747

then in LTspice you must plot the following 'formulas' to get the BH Curve: H=NI/pathlength = 1550*I/1A Bup = (.1202*(1550*I(L1)+99.55)/(abs(1550*I(L1)+99.55)+99.55*13.12) +

Can't remember if those are ceneric constants, or constants just for THIS model. I either get the 'going up' side or the 'going down side' but nothing like I used to get with PSpice DOS version.

By the way, you'll find that LTspice's curve fit for the Chan model is excellent! PSpice's Jiles-Atherton model used to make hour glass shaped hysteresis curves that were incredibly difficult to make square. But, LTspice does fairly well, by just supplying two terms Bsat and the Br [where it hits the axis] and you get a decent looking curve.

Jim, THAT's uncharacteristically vague.See the reply to Jamie for the way to make LTspice do similar plot to what PSpice DOS version used to do. I say 'similar' because I have not been able to get the ends of the curve to touch each other, get close, but no cigars..

FOUND IT! this runs on LTspice

BHCURVE - GENERATES A BH CURVE FOR K528T500_3C8 CORE

• Plot results as V(12)/1V or V(22)/1V or V(32)/1V vs V(20)/1V .TRAN 1 6 0 10uS .OPTIONS ITL5=0
• constant absolute permeability = 4pi*1e-7 .param uo=1.256637e-6
• 3C8 material parameters in MKS units
• Note derived from inspection of Microsim PSpice results .param Hc1=167.1127 .param Bs1=.49 .param Br1=.4575
• Specific core parameters in MKS units .param Lm1=.1290396 .param A1=327.1756e-6 .param Lg1=0 .param N1=20
• I1 0 1 SIN(0 .1 1 1) I2 0 1 SIN(0 .2 1 2) I3 0 1 SIN(0 .8 1 3) I4 0 1 SIN(0 1.6 1 4) R1 1 0 1 L1 1 0 Hc={Hc1} Bs={Bs1} Br={Br1} A=327.1756e-6 Lm={Lm1} Lg={Lg1} N={N1}

• From LTspice manual on page 130 and 131 Use B sources to plot results: Bup 12 0 V={(Bs1*(N1*I(L1)/Lm1+Hc1)/(abs(N1*I(L1)/Lm1+Hc1)+Hc1*(Bs1/ Br1-1)) + uo*N1*I(L1)/Lm1)/1A} Bdn 22 0 V={(Bs1*(N1*I(L1)/Lm1-Hc1)/(abs(N1*I(L1)/Lm1-Hc1)+Hc1*(Bs1/ Br1-1)) + uo*N1*I(L1)/Lm1)/1A} Bmag 32 0 V={(V(12)+V(22))/2}
• assuming flux is contained in the core, H = N1*I(L1)/Lm1 B_H 20 0 V={N1*I(L1)/Lm1/1A} .PROBE .END

then, plot V(12) and V(22) vs V(20) and you get the hysteresis curve, but the ends don't connect.

enjoy

found it! see the reply to myself to Jamie.

Thanks, Helmut!

Suppose I make parts/symbols as in...

where "MODEL" is subcircuit name.

Does that work in LTspice, and can I change "MODEL" in the schematic? ...Jim Thompson

Whoever helps Jim learn to use LT Spice should charge him for it. His only goal is, he admits, to make money.

"John Larkin" wrote in message news: snipped-for-privacy@4ax.com...

You can define the subckt for the Symbol after you place it. Just right Click on the symbol and Change the 'SpiceModel' Line to your subckt name. Not the same as editing the Attributes for the model file in the Symbol editor.

Cheers