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US Patent 5648664 - BIFET vacuum tube replacement structure
US Patent Issued on July 15, 1997
Estimated Patent Expiration Date:
January 20, 2015Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
Estimated Patent Expiration Date:
January 20, 2015Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.AbstractA BIFET vacuum tube replacement structure includes a plurality of devices that replicate the characteristics of a vacuum tube. The vacuum tube replacement structure has the same pin-out as the vacuum tube being replaced and so can be exchanged directly for a vacuum tube in an audio amplifier. The vacuum tube replacement structure is suitable for use in a wide range of audio amplifier applications without modification to the audio amplifiers. Further, there is no noticeable degradation to the human ear in the sound quality when the vacuum tube replacement structure is used in an audio amplifier in place of a vacuum tube. A unitary device that is a combination of a high impedance bipolar like transistor and a unipolar junction field effect transistor, that is referred to as a BIFET, is used in the vacuum tube replacement structure. In one embodiment, the bipolar like transistor is formed in combination with the gate of the unipolar junction field effect transistor. The vacuum tube replacement structure faithfully replicates input signals at low levels and also slowly and uniformly compresses the input signals at higher drive levels and under overdrive conditions.Other References
| InventorsApplicationNo. 376188 filed on 01/20/1995US Classes:257/135, Vertical (i.e., where the source is located above the drain or vice versa)257/256, Junction field effect transistor (unipolar transistor)257/272, Junction field effect transistor in integrated circuit257/273, With bipolar device257/274, Complementary junction field effect transistors257/E29.313, Vertical transistors (EPO)327/581, Field-effect transistor327/599Vacuum tube typeField of Search257/134, J-FET (junction field effect transistor)257/135, Vertical (i.e., where the source is located above the drain or vice versa)257/256, Junction field effect transistor (unipolar transistor)257/266, With multiple parallel current paths (e.g., grid gate)257/272, Junction field effect transistor in integrated circuit257/273, With bipolar device257/274, Complementary junction field effect transistors315/52, Plural impedance elements327/581, Field-effect transistor327/586, Capacitive diode327/599, Vacuum tube type330/296Including particular biasing arrangementExaminersPrimary: Tran, Minh LoanAttorney, Agent or FirmUS Patent References3742261, 3953808, Solid state amplifierIssued on: 04/27/1976 Inventor: Clark , et al.5321283High frequency JFET Issued on: 06/14/1994 Inventor: Cogan, et al. International ClassesH01L 029/74H01L 029/80 |
