Low phase noise voltage controlled oscillator circuit
AssigneeAiroha Technology Corp.
InventorTzuen-Hsi Huang
Life of this patent
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Abstract
A voltage controlled oscillator (VCO) has an LC tank for generating a sinusoidal wave. The VCO uses a positive feedback circuit electrically connected to the LC tank for amplifying the sinusoidal wave. In addition, the VCO includes a noise reducing circuit having a T-shaped resistor configuration connected to the positive feedback circuit. The use of the T-shaped resistor configuration allows the VCO to reduce phase noise generated by the LC tank, and provide a high SNR.
Claims31
A voltage controlled oscillator comprising:
- an LC tank for generating a sinusoidal wave;
- a positive feedback circuit electrically connected to the LC tank for amplifying the sinusoidal wave;
- a noise reducing circuit comprising a T-shaped resistor configuration connected to the positive feedback circuit for reducing phase noise generated by the LC tank;
- and
- a common-mode compensation circuit electrically connected to the positive feedback circuit for further reducing the phase noise generated by the LC tank.
A voltage controlled oscillator comprising:
- an LC tank for generating a sinusoidal wave;
- a positive feedback circuit electrically connected to the LC tank for amplifying the sinusoidal wave;
- and
- a noise reducing circuit comprising a first resistor connected to the positive feedback circuit for reducing phase noise generated by the LC tank, and two second resistors connected to the first resistor for receiving a DC bias voltage.
A voltage controlled oscillator comprising:
- an LC tank for generating a sinusoidal wave;
- two bipolar junction transistors electrically connected to the LC tank for amplifying the sinusoidal wave;
- two voltage dividers for reducing amplitude of the sinusoidal wave;
- two first resistors each connected to a base of one of the bipolar junction transistors for reducing phase noise generated by the LC tank;
- a second resistor connected to the first resistors for receiving a DC bias voltage;
- a common-mode compensation circuit electrically connected to collectors of the bipolar junction transistors for further reducing the phase noise generated by the LC tank;
- a current mirror for mirroring a current in the common-mode compensation circuit onto the LC tank;
- and
- a source follower electrically connected to the collectors of the bipolar junction transistors for reducing loading effect of a load.
A voltage controlled oscillator comprising:
- an LC tank for generating a sinusoidal wave;
- a positive feedback circuit electrically connected to the LC tank for amplifying the sinusoidal wave;
- a noise reducing circuit comprising a T-shaped resistor configuration connected to the positive feedback circuit for reducing phase noise generated by the LC tank;
- and
- an output buffer electrically connected to the positive feedback circuit for reducing a loading effect of a load.
Dependencies are inferred from the claim text.