Patent ID: 6489853
Filing Date: 2002-12-03
Classification: H03B

Abstract:
An oscillator circuit exhibiting low phase noise characteristics comprising:a transistor having a collector, an emitter and a base; a first capacitor connected between the collector of the transistor and a common potential; a first inductor having a first terminal and a second terminal, said first terminal connected to the junction between the first capacitor and the collector; a second capacitor connected on one side to the second terminal of the first inductor and on the other side to a common potential; a first resistor having a first terminal and a second terminal, said first terminal being connected to the junction between the first inductor and the second capacitor; a second resistor connected between the second terminal of the first resistor and a common potential; a third capacitor connected between a common potential and the junction formed by the first resistor and the second resistor; a D.C. supply voltage terminal connected to the junction formed by the first inductor, the second capacitor and the first resistor; a fourth capacitor having a first and second terminal, the first terminal being connected to the junction formed by the first resistor, the second resistor and the third capacitor and the second terminal being connected to the load input which will receive the oscillating signal; a second inductor having a first terminal and a second terminal, the first terminal being connected between the junction formed by the first resistor, the second resistor, the third capacitor and the fourth capacitor and the second terminal of the second inductor being connected to the base of the transistor; a fifth capacitor connected between the junction formed by the base and the second inductor and the emitter of the transistor; a sixth capacitor having a first plate and a second plate, the first plate being connected to the junction formed by the emitter of the transistor and the fifth capacitor; a third resistor provided with a first and a second terminal, the first terminal of the third resistor being connected to the junction of the emitter of the transistor, the fifth capacitor and the first plate of the sixth capacitor, and the second terminal of the third resistor being connected to the second plate of the sixth capacitor; and a parallel resonant circuit having very low inductive and capacitive reactances and connected to the junction between the second terminal of the third resistor and the sixth capacitor; and said parallel resonant circuit comprising a third and a fourth inductor and a seventh capacitor, both of said inductors being connected at one of their respective ends to said junction between the third resistor and the sixth capacitor, the other end of the third inductor being connected to a common ground and the other end of the fourth inductor being connected in series through said seventh capacitor to a common ground.