Patent ID: 6628181
Filing Date: 2003-09-30
Classification: H03H,H03J

Abstract:
A tuning circuit comprising a resonance circuit consisting of an inductor and a capacitor and a negative resistance circuit connected to the resonance circuit in series;negative resistance control means for setting a negative resistance value of the negative resistance circuit to make an effective resistance value of the tuning circuit to be negative so as to oscillate and for varying said negative resistance value in positive direction; stop holding means for holding a first negative resistance value when an amplitude of an oscillation signal outputted from said resonance circuit becomes a first predetermined value and for outputting a second negative resistance value when said amplitude becomes a second predetermined value of half of the first predetermined value to stop varying of said negative resistance value; and operating means for operating the negative resistance value of said negative resistance circuit to obtain a desired Q of the tuning circuit from said first and second negative resistance values.