公开(公告)号：US11309835B2

公开(公告)日：2022-04-19

申请号：US17306960

申请日：2021-05-04

Applicant: MEDIATEK INC.

Inventor： Sen-You Liu ,  Chien-Wei Chen ,  Keng-Meng Chang ,  Yao-Chi Wang

IPC: H03B5/36

Abstract: A crystal oscillator and a phase noise reduction method thereof are provided. The crystal oscillator may include a crystal oscillator core circuit, a first bias circuit and a phase noise reduction circuit, the first bias circuit is coupled to an output terminal of the crystal oscillator core circuit, and the phase noise reduction circuit is coupled to the output terminal of the crystal oscillator core circuit. In operations of the crystal oscillator, the crystal oscillator core circuit is configured to generate a sinusoidal wave. The first bias circuit is configured to provide a first voltage level to be a bias voltage of the sinusoidal wave. The phase noise reduction circuit is configured to reset the bias voltage of the sinusoidal wave in response to a voltage level of the sinusoidal wave exceeding a specific voltage range.

公开(公告)号：US20230396215A1

公开(公告)日：2023-12-07

申请号：US18088612

申请日：2022-12-25

Applicant: MEDIATEK INC.

Inventor： Keng-Meng Chang ,  Sen-You Liu ,  Yao-Chi Wang

IPC: H03B5/32

CPC classification number: H03B5/32 ,  H03B2200/005 ,  H03B2200/0042 ,  H03B2200/0058

Abstract: A reconfigurable crystal oscillator and a method for reconfiguring a crystal oscillator are provided. The reconfigurable crystal oscillator includes a transconductance circuit, a feedback resistor, a crystal tank, an input-end capacitor and an output-end capacitor. Both of the feedback resistor and the crystal tank are coupled between an input terminal and an output terminal of the transconductance circuit. The input-end capacitor is coupled to the input terminal of the transconductance circuit, and the output-end capacitor is coupled to the output terminal of the transconductance circuit. In particular, the transconductance circuit is configured to provide a transconductance, and when an operation mode of the reconfigurable crystal oscillator is switched, an input-end capacitance of the input-end capacitor and an output-end capacitance of the output-end capacitor are switched, respectively.

公开(公告)号：US20220209714A1

公开(公告)日：2022-06-30

申请号：US17693454

申请日：2022-03-14

Applicant: MEDIATEK INC.

Inventor： Sen-You Liu ,  Chien-Wei Chen ,  Keng-Meng Chang ,  Yao-Chi Wang

IPC: H03B5/36

Abstract: A crystal oscillator and a phase noise reduction method thereof are provided. The crystal oscillator may include a crystal oscillator core circuit, a first bias circuit and a phase noise reduction circuit, the first bias circuit is coupled to an output terminal of the crystal oscillator core circuit, and the phase noise reduction circuit is coupled to the output terminal of the crystal oscillator core circuit. In operations of the crystal oscillator, the crystal oscillator core circuit is configured to generate a sinusoidal wave. The first bias circuit is configured to provide a first voltage level to be a bias voltage of the sinusoidal wave. The phase noise reduction circuit is configured to reset the bias voltage of the sinusoidal wave in response to a voltage level of the sinusoidal wave exceeding a specific voltage range. For example, the specific voltage range is determined according to a second voltage level.

公开(公告)号：US20220069773A1

公开(公告)日：2022-03-03

申请号：US17306960

申请日：2021-05-04

Applicant: MEDIATEK INC.

Inventor： Sen-You Liu ,  Chien-Wei Chen ,  Keng-Meng Chang ,  Yao-Chi Wang

IPC: H03B5/36

Abstract: A crystal oscillator and a phase noise reduction method thereof are provided. The crystal oscillator may include a crystal oscillator core circuit, a first bias circuit and a phase noise reduction circuit, the first bias circuit is coupled to an output terminal of the crystal oscillator core circuit, and the phase noise reduction circuit is coupled to the output terminal of the crystal oscillator core circuit. In operations of the crystal oscillator, the crystal oscillator core circuit is configured to generate a sinusoidal wave. The first bias circuit is configured to provide a first voltage level to be a bias voltage of the sinusoidal wave. The phase noise reduction circuit is configured to reset the bias voltage of the sinusoidal wave in response to a voltage level of the sinusoidal wave exceeding a specific voltage range.

公开(公告)号：US11387781B1

公开(公告)日：2022-07-12

申请号：US17395439

申请日：2021-08-05

Applicant: MEDIATEK INC.

Inventor： Keng-Meng Chang ,  Yao-Chi Wang ,  Yanjie Mo ,  Sen-You Liu ,  Chun-Ming Lin

IPC: H03B5/32 ,  H03K5/00 ,  H03B5/36 ,  H03B5/12 ,  H03L7/00 ,  H03L7/06

Abstract: A fast start-up crystal oscillator (XO) and a fast start-up method thereof are provided. The fast start-up XO may include a XO core circuit, a frequency synthesizer, and a fast start-up interfacing circuit, wherein the frequency synthesizer may include a voltage control oscillator (VCO) and a divider. The XO core circuit generates a XO signal having a XO frequency. The VCO generates a VCO clock having a VCO frequency, and the divider generates a divided clock having a divided frequency, wherein the VCO frequency is divided by a divisor of the divider to obtain the divided frequency. The fast start-up interfacing circuit transmits the divided clock to the XO core circuit, and then generates a reference clock having the XO frequency according to the XO signal. More particularly, the VCO frequency is calibrated according to the reference clock, in order to make the divided frequency approach the XO frequency.

公开(公告)号：US12047038B2

公开(公告)日：2024-07-23

申请号：US18088612

申请日：2022-12-25

Applicant: MEDIATEK INC.

Inventor： Keng-Meng Chang ,  Sen-You Liu ,  Yao-Chi Wang

IPC: H03B5/32 ,  H03B5/36

CPC classification number: H03B5/32 ,  H03B5/366 ,  H03B2200/0042 ,  H03B2200/005 ,  H03B2200/0058 ,  H03B2200/009

Abstract: A reconfigurable crystal oscillator and a method for reconfiguring a crystal oscillator are provided. The reconfigurable crystal oscillator includes a transconductance circuit, a feedback resistor, a crystal tank, an input-end capacitor and an output-end capacitor. Both of the feedback resistor and the crystal tank are coupled between an input terminal and an output terminal of the transconductance circuit. The input-end capacitor is coupled to the input terminal of the transconductance circuit, and the output-end capacitor is coupled to the output terminal of the transconductance circuit. In particular, the transconductance circuit is configured to provide a transconductance, and when an operation mode of the reconfigurable crystal oscillator is switched, an input-end capacitance of the input-end capacitor and an output-end capacitance of the output-end capacitor are switched, respectively.

公开(公告)号：US11671056B2

公开(公告)日：2023-06-06

申请号：US17693454

申请日：2022-03-14

Applicant: MEDIATEK INC.

Inventor： Sen-You Liu ,  Chien-Wei Chen ,  Keng-Meng Chang ,  Yao-Chi Wang

IPC: H03B5/36

CPC classification number: H03B5/36 ,  H03B5/362 ,  H03B5/364 ,  H03B2200/009

Abstract: A crystal oscillator and a phase noise reduction method thereof are provided. The crystal oscillator may include a crystal oscillator core circuit, a first bias circuit and a phase noise reduction circuit, the first bias circuit is coupled to an output terminal of the crystal oscillator core circuit, and the phase noise reduction circuit is coupled to the output terminal of the crystal oscillator core circuit. In operations of the crystal oscillator, the crystal oscillator core circuit is configured to generate a sinusoidal wave. The first bias circuit is configured to provide a first voltage level to be a bias voltage of the sinusoidal wave. The phase noise reduction circuit is configured to reset the bias voltage of the sinusoidal wave in response to a voltage level of the sinusoidal wave exceeding a specific voltage range. For example, the specific voltage range is determined according to a second voltage level.