Four-phase clock generator with timing sequence self-detection

• US 9,455,823 B2
• Filed: 05/25/2015
• Issued: 09/27/2016
• Est. Priority Date: 02/24/2015
• Status: Active Grant

• Current Assignee: PixArt Imaging Incorporated
• Original Assignee: PixArt Imaging Incorporated
• Inventors: Hsu, Cheng-Seng
• Primary Examiner(s): Perez, James M
• Application Number:
  US14/720,933
• Publication Number:
  US 20160248578A1
• Time in Patent Office: 491 Days
• Field of Search: 375211-215, 375/286, 375293-294, 375316-352, 375354-376
• US Class Current: 1/1
• CPC Class Codes: H03L 7/0996 Selecting a signal among the plurality of phase-shifted signals produced by the ring oscillator

Abstract

A four-phase clock generator with timing sequence self-detection including a phase-locked loop (PLL), a frequency dividing module, and a detection and control module. The PLL generates a first to a fourth reference clock signal with the same frequency, respectively, wherein each consecutive two of the first to the fourth reference clock signals have a 90-degree phase difference. The frequency dividing module is coupled to the PLL and determines whether to perform frequency dividing on the first to the fourth reference clock signals to obtain a first through a fourth output clock signal according to a first control signal. The detection and control module is coupled to the frequency dividing module and detects a timing sequence of the first to the fourth output clock signals to output the first control signal accordingly.

Claims

1. A four-phase clock generator with timing sequence self-detection, comprising:

a phase-locked loop (PLL) for generating a first to a fourth reference clock signal with a same frequency, respectively, wherein each consecutive two of said first to said fourth reference clock signals have a 90-degree phase difference;

a frequency dividing module being coupled to said phase-locked loop to determine whether to perform frequency dividing on said first to said fourth reference clock signals to obtain a first through a fourth output clock signal according to a first control signal, wherein said frequency dividing module is triggered by said fourth reference clock signal to start perform frequency dividing; and

a detection and control module being coupled to said frequency dividing module to detect a timing sequence of said first to said fourth output clock signals to output said first control signal accordingly;

wherein when the phase difference for each consecutive two of the four reference clock signals is no longer 90-degree, said first control signal controls said frequency dividing module to stop performing frequency dividing on said first to said fourth reference clock signals since said timing sequence of said first to said fourth output clock signals is incorrect.

2. The four-phase clock generator of claim 1, wherein said phase-locked loop comprises at least one voltage-controlled oscillator (VCO) to generate said first to said fourth reference clock signals.

3. The four-phase clock generator of claim 1, wherein said frequency dividing module comprises:

a first D-type flip-flop being coupled to said phase-locked loop and said detection and control module, said first D-type flip-flop comprising an inverting reset terminal receiving said first control signal and a non-inverting output terminal outputting a second control signal; and

a frequency dividing unit being coupled to said first D-type flip-flop and said phase-locked loop to determine whether to perform frequency dividing on said first to said fourth reference clock signals to obtain said first to said fourth output clock signals according to said second control signal.

4. The four-phase clock generator of claim 3, wherein a clock input terminal and a data input terminal of said first D-type flip-flop receive, respectively, said fourth reference clock signal and a clock output enabling signal, wherein said first control signal is triggered by a rising edge in said fourth reference clock signal to output said clock output enabling signal as said second control signal when said first control signal is true.

5. The four-phase clock generator of claim 4, wherein said frequency dividing unit further comprises:

four D-type flip-flops being a second to a fifth D-type flip-flops, wherein an inverting output terminal of each of said D-type flip-flops is correspondingly coupled to a data input terminal of one of said D-type flip-flops, clock input terminals of said second and said third D-type flip-flops receive said first reference clock signal, clock input terminals of said fourth and said fifth D-type flip-flops receive said third reference clock signal, and inverting reset terminals of said second to said fifth D-type flip-flops receive said second control signal;

wherein said frequency dividing unit generates said first to said fourth output clock signals according to non-inverting output terminals of said second to said fifth D-type flip-flops, respectively, when said second control signal is true.

6. The four-phase clock generator of claim 5, wherein said second D-type flip-flop is triggered by a rising edge in said first reference clock signal to output said first output clock signal at said non-inverting output terminal of said second D-type flip-flop, said third D-type flip-flop is triggered by a falling edge in said first reference clock signal to output said second output clock signal at said non-inverting output terminal of said third D-type flip-flop, said fourth D-type flip-flop is triggered by a falling edge in said third reference clock signal to output said third output clock signal at said non-inverting output terminal of said fourth D-type flip-flop, and said fifth D-type flip-flop is triggered by a rising edge in said third reference clock signal to output said fourth output clock signal at said non-inverting output terminal of said fifth D-type flip-flop.

7. The four-phase clock generator of claim 6, wherein said detection and control module comprises:

a sixth D-type flip-flop comprising a clock input terminal and a data input terminal receiving, respectively, consecutive two of said first to said fourth output clock signals to output said first control signal at a non-inverting output terminal thereof when said sixth D-type flip-flop is triggered at said clock input terminal thereof by a rising edge or a falling edge in said output clock signals received.

8. The four-phase clock generator of claim 7, wherein said detection and control module further comprises a pulse generator, said pulse generator being triggered by a falling edge in said second control signal to output a pulse signal to a set terminal of said sixth D-type flip-flop.

9. The four-phase clock generator of claim 8, wherein an inverting reset terminal of said sixth D-type flip-flop receives a system voltage.

10. The four-phase clock generator of claim 6, wherein said detection and control module comprises:

M sixth D-type flip-flops, each comprising a clock input terminal and a data input terminal receiving, respectively, consecutive two of said first to said fourth output clock signals to output a detection signal at a non-inverting output terminal thereof when each of said sixth D-type flip-flops is triggered at said clock input terminal thereof by a rising edge or a falling edge in said output clock signals received; and

an AND gate being coupled to said non-inverting output terminals of said sixth D-type flip-flops to output said first control signal according to said detection signal;

wherein M is a positive integer larger than 1.

11. The four-phase clock generator of claim 10, wherein said detection and control module further comprises a pulse generator, said pulse generator being triggered by a falling edge in said second control signal to output a pulse signal to a set terminal of each of said sixth D-type flip-flops.

12. The four-phase clock generator of claim 11, wherein an inverting reset terminal of each of said sixth D-type flip-flops receives a system voltage.