Patents by Inventor Jieh-Tsong Wu

Jieh-Tsong Wu has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5486794
    Abstract: A variable frequency oscillator which can be implemented entirely in a semiconductor chip, which is variable over a broad frequency range and which has relatively low phase noise, includes a variable impedance circuit, a reactive load connected to an output terminal pair of the variable impedance circuit, and a negative impedance circuit having an output terminal pair connected to the output terminal pair of the variable impedance circuit. In one embodiment, the negative impedance circuit has an input terminal pair connected to an input terminal pair of the variable impedance circuit to serve as a positive feedback path for the variable impedance circuit. In another embodiment, the negative impedance circuit includes a pair of level shifters which ensure that the variable impedance circuit is properly biased and works in a forward active region.
    Type: Grant
    Filed: December 15, 1994
    Date of Patent: January 23, 1996
    Assignee: National Science Council of R.O.C.
    Inventors: Jieh-Tsong Wu, Wei-Zen Shen
  • Patent number: 5475327
    Abstract: A variable impedance circuit includes a differential circuit, an impedance element, a variable current attenuator and a pair of level shifters. The differential circuit includes a transistor pair with a pair of input terminals, a pair of output terminals, and a pair of emitters. The impedance element is connected between the emitters of the transistor pair. The variable current attenuator has a pair of input terminals connected respectively to the output terminals of the transistor pair, a pair of output terminals, and a pair of control inputs for receiving a control voltage to vary the current gain of the variable current attenuator. Each of the level shifters has an input terminal connected to a respective one of the output terminals of the variable current attenuator, and an output terminal connected to a respective one of the input terminals of the transistor pair. The level shifters ensure that the transistor pair and the variable current attenuator are properly biased.
    Type: Grant
    Filed: November 18, 1994
    Date of Patent: December 12, 1995
    Assignee: National Science Council of R.O.C.
    Inventors: Jieh-Tsong Wu, Wei-Zen Chen