The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 21, 2000
Filed:
Mar. 18, 1999
Yap Hwa Seng, Sinapore, SG;
Aruna Bopaiah Ajjikuttira, Sinapore, SG;
Tritech Microelectronics Ltd., Singapore, SG;
Abstract
An oscillator circuit, whose output signal has minimum fluctuation with changes in temperature, has an amplifier. Within the amplifier, a compensation resistor is connected to compensate for changes in amplitude and frequency of the output signal with temperature. A first impedance is connected between an output and a first input of the amplifier, a second impedance is connected between the first input and a second input, and a third impedance is connected between the output and the second input. A method for designing the oscillator begins by choosing an inductor with a high quality factor and a low temperature coefficient. The interconnections are designed to minimize temperature effects of parasitic impedances. A degenerative resistor is connected between the emitter of the bipolar transistor and the emitter resistor. The degenerative resistor varies in resistance with a change in temperature opposite that of an input resistance of the bipolar junction transistor. The first and second capacitors are selected to minimize the effect of variation of the parasitic impedance. The oscillator is converted to a frequency shift keying oscillator by adding frequency shifting means to modulate the frequency of the output signal between a first frequency and a second frequency according to a state of a digital input signal. The method of designing the oscillator as a frequency shift keying oscillator requires selecting an on-resistance of the frequency shifting means to prevent the first frequency and the second frequency from fluctuating with temperature.