Frequency divider, clock generating apparatus, and method capable of calibrating frequency drift of oscillator

• US 9,692,395 B2
• Filed: 03/10/2016
• Issued: 06/27/2017
• Est. Priority Date: 10/22/2012
• Status: Active Grant

• Current Assignee: MediaTek, Inc.
• Original Assignee: MediaTek, Inc.
• Inventors: Liu, Shiue-Shin, Ying, Yu-Ming
• Primary Examiner(s): POOS, JOHN W
• Application Number:
  US15/067,141
• Publication Number:
  US 20160197599A1
• Time in Patent Office: 474 Days
• Field of Search: 327113, 327115, 327156, 327158, 327161
• CPC Class Codes: H03K 3/013 Modifications of generator to prevent operation by noise or interference
• CPC Class Codes: H03K 7/06 Frequency or rate modulation, i.e. PFM or PRM
• CPC Class Codes: H03L 1/022 by indirect stabilisation, i.e. by generating an electrical correction signal which is a function of the temperature H03L1/021 takes precedence
• CPC Class Codes: H03L 7/1974 for fractional frequency division
• CPC Class Codes: H03L 7/1976 using a phase accumulator for controlling the counter or frequency divider

Abstract

A clock generating apparatus includes an oscillator and a frequency synthesizer. The oscillator is utilized for generating a reference clock signal. The frequency synthesizer is coupled to the oscillator and utilized for synthesizing a target clock signal in accordance with the reference clock signal and a frequency division factor that has been adjusted or compensated, and outputting the target clock signal as an output of the clock generating apparatus.

Claims

1. A clock generating apparatus, comprising:

an oscillator, for generating a reference clock signal; and

a fractional divider, directly or indirectly coupled to the oscillator, for receiving the reference clock signal and outputting a target clock signal, wherein the target clock signal is adjusted according to at least a process related parameter and/or at least a temperature related parameter, wherein the fractional divider is an open-loop circuit, the at least a process related parameter corresponding to process fabrication information, the at least a temperature related parameter corresponding to temperature condition information;

wherein the fractional divider includes a phase control circuit having a phase selector and a phase interpolator, wherein the phase selector selects at least two phase shifts from different phase characteristics generated based on the reference clock signal, and the phase interpolator further interpolates the selected phase shifts to generate the target clock signal.

2. The clock generating apparatus of claim 1, wherein the phase control circuit further comprises:

a sigma-delta modulator (SDM) coupled to the phase selector and the phase interpolator, for respectively controlling the phase selector and the phase interpolator based on the process related parameter and/or the temperature related parameter.

3. The clock generating apparatus of claim 1, wherein the fractional divider is incorporated or further coupled to a frequency synthesizer.

4. The clock generating apparatus of claim 3, wherein the frequency synthesizer includes a phase frequency detector, and the target clock signal outputted from the fractional divider is further inputted to the phase frequency detector.

5. The clock generating apparatus of claim 1, wherein the fractional divider includes a digital processing block arranged to determine a frequency division factor based on the process related parameter and/or the temperature related parameter.

6. The clock generating apparatus of claim 5, wherein the digital processing block is arranged to select the process related parameter from a set of process parameters and/or the temperature parameter from a set of temperature related parameters by referring to a current fabrication process or a current temperature.

7. The clock generating apparatus of claim 6, further comprising:

a table recording the set of process related parameters and/or the set of temperature related parameters.

8. The clock generating apparatus of claim 1, being installed on a single integrated circuit chip.

9. The clock generating apparatus of claim 1, wherein the oscillator includes a LC resonator.

10. A clock generating apparatus, comprising:

an oscillator, for generating a reference clock signal; and

a fractional divider, directly or indirectly coupled to the oscillator, for receiving the reference clock signal and outputting a target clock signal, wherein the target clock signal is adjusted according to at least a process related parameter and/or at least a temperature related parameter, the at least a process related parameter corresponding to process fabrication information, the at least a temperature related parameter corresponding to temperature condition information;

wherein the fractional divider includes a phase control circuit having a phase selector and a phase interpolator, wherein the phase selector selects at least two phase shifts from different phase characteristics generated based on the reference clock signal, and the phase interpolator further interpolates the selected phase shifts to generate the target clock signal.

11. The clock generating apparatus of claim 10, wherein the fractional divider is an open loop circuit.

12. The clock generating apparatus of claim 10, wherein the fractional divider is not a PLL circuit.

13. The clock generating apparatus of claim 10, wherein the fractional divider does not have a feedback path.

14. The clock generating apparatus of claim 10, wherein the phase control circuit further comprises:

a sigma-delta modulator (SDM) coupled to the phase selector and the phase interpolator, for respectively controlling the phase selector and the phase interpolator based on the process related parameter and/or the temperature related parameter.

15. The clock generating apparatus of claim 10, wherein the fractional divider is incorporated or further coupled to a frequency synthesizer.

16. The clock generating apparatus of claim 15, wherein the frequency synthesizer includes a phase frequency detector, and the target clock signal outputted from the fractional divider is further inputted to the phase frequency detector.

17. The clock generating apparatus of claim 10, wherein the fractional divider includes a digital processing block arranged to determine a frequency division factor based on the process related parameter and/or the temperature related parameter.

18. The clock generating apparatus of claim 10, being installed on a single integrated circuit chip.

19. The clock generating apparatus of claim 10, wherein the oscillator includes a LC resonator.