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While making a dual-gate MOSFET subcircuit, something occurred I don't remember seeing before. If I choose Spice netlist versus SpiceLibComp, the model "schematic" and dual-gate MOSFET symbol are overlaid when placed on schematic. The OpAmp library was made using Spice netlist and never had this problem.
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Replies: 5 comments
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@tomhajjar , I have just tried to recreate the device from scratch using SPICE file and I cannot reproduce the problem. Everything works as expected. I have also inspected my projects containing subcircuits made from SPICE file. Everything works as expected too. I suspect the schematic file became broken by unknown reason. I sucpect this may be related to the recent schematic class refactoring. Also please keep in mind that Qucs-S contains BF998 model since v0.0.23 release. You don't need to recreate it. I don't consider the update of this library. Other dual gate MOSFETs like BF961 could be added, but I didn't find the SPICE models for them. |
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@tomhajjar You have incorrect port number |
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Thanks for the catch. I was porting an LTspice project by Gunthard Kraus over to Qucs-S and forgot BF998 was native. I also wanted to add a dual-gate device to schematic_symbols.sch. The LTspice example deletes the C=/L= entries in BF998.cir. ngspice doesn't say in the manual this format is acceptable but it must be since I confirmed the S-parameters are the same for the library model and the subcircuit I made.
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Here is Bordodynov's dual gate mosfet library. |
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I found the s-parameters for the BF998 and they compare favorably with the Spice model. I converted a LTspice 137MHz LNA project by the late Gunthard Kraus over to Qucs-S. S11 looks sketchy but it matches the original data where s11 -> NFopt.
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@tomhajjar , I have just tried to recreate the device from scratch using SPICE file and I cannot reproduce the problem. Everything works as expected. I have also inspected my projects containing subcircuits made from SPICE file. Everything works as expected too. I suspect the schematic file became broken by unknown reason. I sucpect this may be related to the recent schematic class refactoring.
Also please keep in mind that Qucs-S contains BF998 model since v0.0.23 release. You don't need to recreate it. I don't consider the update of this library. Other dual gate MOSFETs like BF961 could be added, but I didn't find the SPICE models for them.