OSCILLATING APPARATUS HAVING CURRENT COMPENSATING DEVICE FOR PROVIDING COMPENSATING CURRENT TO COMPENSATE FOR CURRENT REDUCTION OF TRANSCONDUCTIVE DEVICE AND METHOD THEREOF

• US 20080266007A1
• Filed: 04/25/2007
• Published: 10/30/2008
• Est. Priority Date: 04/25/2007
• Status: Abandoned Application

• Current Assignee: MediaTek, Inc.
• Original Assignee: MediaTek, Inc.
• Inventors: Tsai, Ming-Da
• Application Number:
  US11/740,282
• Publication Number:
  US 20080266007A1
• Time in Patent Office: Days
• US Class Current: 331/117FE
• CPC Class Codes: H03B 2201/025 the means being an electronic switch for switching in or out oscillator elements
• CPC Class Codes: H03B 5/1215 the current source or degeneration circuit being in common to both transistors of the pair, e.g. a cross-coupled long-tailed pair
• CPC Class Codes: H03B 5/1228 the amplifier comprising one or more field effect transistors
• CPC Class Codes: H03B 5/124 the means comprising a voltage dependent capacitance
• CPC Class Codes: H03B 5/1265 switched capacitors

Abstract

According to an embodiment of the present invention, an oscillating apparatus is provided. The oscillating apparatus generates an oscillating signal, and the oscillating apparatus includes a resonating device, a transconductive device, a biasing device, and a current compensating device. The resonating device generates the oscillating signal; the transconductive device is coupled to the resonating device for providing the resonating device with a positive feedback loop; the biasing device is coupled to the transconductive device for providing the transconductive device with a biasing current; and the current compensating device is coupled between the resonating device and the biasing device for providing the biasing device with a compensating current to compensate for a current reduction of the transconductive device.

Claims

1. An oscillating apparatus, for generating an oscillating signal, the oscillating apparatus comprising:

a resonating device, for generating the oscillating signal;

a transconductive device, coupled to the resonating device, for providing the resonating device with a positive feedback loop;

a biasing device, coupled to the transconductive device, for providing the transconductive device with a biasing current; and

a current compensating device, coupled between the resonating device and the biasing device, for providing the biasing device with a compensating current to compensate for a current reduction of the transconductive device.

2. The oscillating apparatus of claim 1, wherein the current compensating device generates a periodic current corresponding to the oscillating signal as the compensating current.

3. The oscillating apparatus of claim 1, wherein the current compensating device is a conductive line having a first node directly connected to a common mode node of the resonating device and a second node directly connected to the common mode node of the transconductive device.

4. The oscillating apparatus of claim 1, wherein the current compensating device is an inductive device having a first node coupled to a common mode node of the resonating device and a second node coupled to the common mode node of the transconductive device.

5. The oscillating apparatus of claim 1, wherein the current compensating device is a capacitive device having a first node coupled to a common mode node of the resonating device and a second node coupled to the common mode node of the transconductive device.

6. A method for reducing a phase noise of an oscillating signal generated from an oscillating apparatus, comprising:

designing the oscillating apparatus to have a resonating device for generating the oscillating signal, a transconductive device for providing the resonating device with a positive feedback loop, and a biasing device for providing the transconductive device with a biasing current; and

directly connecting a common mode node of the resonating device and a common mode node of the transconductive device.

7. A method for reducing a phase noise of an oscillating signal generated from an oscillating apparatus, comprising:

designing the oscillating apparatus to have a resonating device for generating the oscillating signal, a transconductive device for providing the resonating device with a positive feedback loop, and a biasing device for providing the transconductive device with a biasing current; and

coupling an inductive device between a common mode node of the resonating device and a common mode node of the transconductive device.

8. A method for reducing a phase noise of an oscillating signal generated from an oscillating apparatus, comprising:

designing the oscillating apparatus to have a resonating device for generating the oscillating signal, a transconductive device for providing the resonating device with a positive feedback loop, and a biasing device for providing the transconductive device with a biasing current; and

coupling a capacitive device between a common mode node of the resonating device and a common mode node of the transconductive device.