fonction de transfert avec ngspice

Bonsoir, J'aimerais effectuer la fonction de transfert d'un filtre. Voici le fichier a.sch :

Fonction de transfert d'un filtre de Wien ISRC 1 0 AC 1 R1 1 2 1k C1 2 3 1u R2 3 0 1k C2 3 0 1u .AC DEC 10 1 10K .END

J'utilise ngspice-19 .

Je lance la simulation et voici les messages d'erreurs :

Doing analysis at TEMP =3D 27.000000 and TNOM =3D 27.000000

Warning: Source isrc has no value, DC 0 assumed

Warning: singular matrix: check nodes 1 and 1

Note: starting dynamic Gmin stepping Trying gmin =3D 1.0000E-03 Note: One successful Gmin step Trying gmin =3D 1.0000E-04 Note: One successful Gmin step Trying gmin =3D 1.0000E-05 Note: One successful Gmin step Trying gmin =3D 1.0000E-06 Note: One successful Gmin step Trying gmin =3D 1.0000E-07 Note: One successful Gmin step Trying gmin =3D 1.0000E-08 Note: One successful Gmin step Trying gmin =3D 1.0000E-09 Note: One successful Gmin step Trying gmin =3D 1.0000E-10 Note: One successful Gmin step Trying gmin =3D 1.0000E-11 Note: One successful Gmin step Trying gmin =3D 1.0000E-12 Note: One successful Gmin step Trying gmin =3D 1.0000E-12 Note: One successful Gmin step Warning: singular matrix: check nodes 1 and 1

Warning: Dynamic Gmin stepping failed Note: starting source stepping Supplies reduced to 0.0000% Warning: singular matrix: check nodes 1 and 1

Trying gmin =3D 1.0000E-02 Note: One successful Gmin step Trying gmin =3D 1.0000E-03 Note: One successful Gmin step Trying gmin =3D 1.0000E-04 Note: One successful Gmin step Trying gmin =3D 1.0000E-05 Note: One successful Gmin step Trying gmin =3D 1.0000E-06 Note: One successful Gmin step Trying gmin =3D 1.0000E-07 Note: One successful Gmin step Trying gmin =3D 1.0000E-08 Note: One successful Gmin step Trying gmin =3D 1.0000E-09 Note: One successful Gmin step Trying gmin =3D 1.0000E-10 Note: One successful Gmin step Trying gmin =3D 1.0000E-11 Note: One successful Gmin step Trying gmin =3D 1.0000E-12 Note: One successful Gmin step Note: One successful source step Supplies reduced to 0.1000% Warning: singular matrix: check nodes 1 and 1

Supplies reduced to 0.0000% Warning: singular matrix: check nodes 1 and 1

Warning: source stepping failed

AC operating point failed -

Last Node Voltages

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Node Last Voltage Previous Iter

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doAnalyses: iteration limit reached

run simulation(s) aborted

Qu'est ce qui ne va pas ? Merci pour votre aide, C=E9dric