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TINA macro for fast JFETs

Julien TAIEB
Prodigy 165 points
Other Parts Discussed in Thread: TINA-TI

Here is a newbie question.

I just started to work with TINA. I'm really not familiar with any spice-base app.

I tried to use some fast JFET together with some TI OPAMP. It seems that the JFET model don't exist

I found the SPICE model for BF862 :

* BF862 SPICE MODEL MARCH 2007 NXP SEMICONDUCTORS
* ENVELOPE SOT23
* JBF862: 1, Drain, 2,Gate, 3,Source

Ld 1 4 L= 1.1nH
Ls 3 6 L= 1.25nH
Lg 2 5 L= 0.78nH
Rg 5 7 R= 0.535 Ohm
Cds 1 3 C= 0.0001pF
Cgs 2 3 C= 1.05pF
Cgd 1 2 C= 0.201pF
Co 4 6 C= 0.35092pF

JBF862 model parameters:

.model JBF862 NJF(Beta=47.800E-3 Betatce=-.5 Rd=.8 Rs=7.5000 Lambda=37.300E-3 Vto=-.57093
+ Vtotc=-2.0000E-3 Is=424.60E-12 Isr=2.995p N=1 Nr=2 Xti=3 Alpha=-1.0000E-3
+ Vk=59.97 Cgd=7.4002E-12 M=.6015 Pb=.5 Fc=.5 Cgs=8.2890E-12 Kf=87.5E-18
+ Af=1)

ENDS BF862

but how to make a .lib file out of it ?

Cheers

Julien

  • 0
    TI__Mastermind 41310 points

    Julien,

    The "Spice" model is missing a few items. Not sure why NXP would put this up as it cannot be used in it's current form. First, there is no placement in the netlist of the JBF862 JFET model. Second, there is no .SUBCKT statement for the BF862. I am unsure of the parasitics and how they are connected to the JFET for this model. I would contact NXP directly and ask them for assistance with the model provided. The full file should have:

    .SUBCKT BF862 1 2 3 (the pins would correspond to the pins on the BF862)

    J1 <node1> <node2> <node3> JBF862    - where nodeX is the connection to the parasitic network included. (my guess would be 4 6 5 in this case)

    These two lines will dictate how the JFET and parasitics are connected with relationship to the pinout of the BF862. Once you have the complete .SUBCKT, simply save the file as a .lib file (BF862.lib for example) and use the New Macro Wizard in TINA-TI to import it into your simulation.

    Britt

  • 0 in reply to Britt Brooks - Online Design Tools
    Expert 2056 points

    Did you make a complete file and use it?

    NXP's file is here http://www.nxp.com/documents/spice_model/BF862.prm

    *   BF862 SPICE MODEL MARCH 2007 NXP SEMICONDUCTORS
*   ENVELOPE    SOT23
*   JBF862: 1, Drain,  2,Gate,  3,Source

  Ld  1 4  L=	1.1nH
  Ls  3 6  L=	1.25nH
  Lg  2 5  L=	0.78nH
  Rg  5 7  R=	0.535 Ohm
  Cds  1 3  C=	0.0001pF
  Cgs  2 3  C=	1.05pF
  Cgd  1 2  C=	0.201pF
  Co  4 6  C=	0.35092pF

JBF862  model parameters:

.model JBF862 NJF(Beta=47.800E-3 Betatce=-.5 Rd=.8 Rs=7.5000 Lambda=37.300E-3 Vto=-.57093
+ Vtotc=-2.0000E-3 Is=424.60E-12 Isr=2.995p N=1 Nr=2 Xti=3 Alpha=-1.0000E-3
+ Vk=59.97 Cgd=7.4002E-12 M=.6015 Pb=.5 Fc=.5 Cgs=8.2890E-12 Kf=87.5E-18
+ Af=1)

ENDS BF862



    There's also one here:
    http://www.diyaudio.com/forums/solid-state/71189-john-curls-blowtorch-preamplifier-1324.html#post1720790

     

    *DEVICE=BF862, NJF
.SUBCKT BF862 1 2 3
+ params:
+ BETA=47.80m
JBF862 4 7 6 J_BF862
Ld 1 4 1.1n
Ls 3 6 1.25n
Lg 2 5 0.78n
Rg 5 7 0.535
Cds 1 3 0.0001p
Cgs 2 3 1.05p
Cgd 1 2 0.201p
Co 4 6 0.35092p
*
.model J_BF862 NJF(Beta={BETA} Betatce=-.5 Rd=.8 Rs=7.5000
+ Lambda=37.300E-3 Vto=-.57093 Vtotc=-2.0000E-3 Is=424.60E-12
+ Isr=2.995p N=1 Nr=2 Xti=3 Alpha=-1.0000E-3 Vk=59.97
+ Cgd=7.4002E-12 M=.6015 Pb=.5 Fc=.5 Cgs=8.2890E-12 Kf=87.5E-18
+ Af=1)
.ENDS BF862

     

    *   BF862 SPICE MODEL MARCH 2007 NXP SEMICONDUCTORS
*   ENVELOPE    SOT23
*   JBF862: 1, Drain,  2,Gate,  3,Source

  Ld  1 4  L=	1.1nH
  Ls  3 6  L=	1.25nH
  Lg  2 5  L=	0.78nH
  Rg  5 7  R=	0.535 Ohm
  Cds  1 3  C=	0.0001pF
  Cgs  2 3  C=	1.05pF
  Cgd  1 2  C=	0.201pF
  Co  4 6  C=	0.35092pF

JBF862  model parameters:

.model JBF862 NJF(Beta=47.800E-3 Betatce=-.5 Rd=.8 Rs=7.5000 Lambda=37.300E-3 Vto=-.57093
+ Vtotc=-2.0000E-3 Is=424.60E-12 Isr=2.995p N=1 Nr=2 Xti=3 Alpha=-1.0000E-3
+ Vk=59.97 Cgd=7.4002E-12 M=.6015 Pb=.5 Fc=.5 Cgs=8.2890E-12 Kf=87.5E-18
+ Af=1)

ENDS BF862
  • 0 in reply to Britt Brooks - Online Design Tools
    Expert 2056 points

    Thanks!  Here's the one I made from the DIYAUDIO post:

    diyaudio's BF862.TSM

    I don't know enough about spice transistor models to know which is better though (or if I even got the pinouts right....)

    Actually the file you sent doesn't work for me.  Have you tested it?

  • 0 in reply to Jonathan9420
    Prodigy 165 points

    same problem on my side.

    I get crazy results with that model. I had to start with a basic JFET model and try to modify it to get something reasonable.

    However, I don't like that way of working.

  • 0 in reply to Julien TAIEB
    Prodigy 130 points

    TINA  SPICE model for BF862 :

    *   BF862 SPICE MODEL MARCH 2007 NXP SEMICONDUCTORS

    *   ENVELOPE    SOT23

    *   JBF862: 1, Drain,  2,Gate,  3,Source

    .SUBCKT BF862 1 2 3

     Ld   1 4  1.1n

     Ls   3 6  1.25n

     Lg   2 5  0.78n

     Rg   5 7  0.535

     Cds  1 3  0.0001p

     Cgs  2 3  1.05p

     Cgd  1 2  0.201p

     Co   4 6  0.35092p

     J1 4 7 6 JBF862

    .model JBF862 NJF(Beta=47.800E-3 Betatce=-.5 Rd=.8 Rs=7.5000 Lambda=37.300E-3 Vto=-.57093

    + Vtotc=-2.0000E-3 Is=424.60E-12 Isr=2.995p N=1 Nr=2 Xti=3 Alpha=-1.0000E-3

    + Vk=59.97 Cgd=7.4002E-12 M=.6015 Pb=.5 Fc=.5 Cgs=8.2890E-12 Kf=87.5E-18

    + Af=1)

    .ENDS BF862

  • 0 in reply to Britt Brooks - Online Design Tools
    Expert 2056 points

    Britt Brooks - WEBENCH® Design Center said:

    FYI...

    (Please visit the site to view this file)

    Britt

    That one doesn't work:

    Here's one I made from these SPICE files that works:

    3441.BF862.TSM

    The gain of a buffer is 0 dB as expected, and the noise at 100 kHz is 0.7977nV, which matches the datasheet's value of 0.8 nV.  However, the noise at low frequencies doesn't match this article:

    Is the model wrong at low frequencies, or is the test circuit not appropriate?

  • 0 in reply to Jonathan9420
    Prodigy 130 points

    Jonathan9420 said:
    Is the model wrong at low frequencies, or is the test circuit not appropriate?

    The JFET model noise characteristics are determined by last two parameters:
    Kf...flicker-noise coefficient
    Af...flicker-noise exponent (default value 1).

    If you want to see one that was measured in the attached article, then change the Af value from 1 to 1.2 in the model.

    I hope it helps.