Device and method for automatically adjusting a phase-locked loop

• US 5,268,655 A
• Filed: 05/27/1992
• Issued: 12/07/1993
• Est. Priority Date: 05/27/1992
• Status: Expired due to Term

• Current Assignee: Motorola Mobility, Inc. (Lenovo Group Ltd.)
• Original Assignee: Codex Corporation
• Inventors: Dong, Ping
• Primary Examiner(s): Grimm, Siegfried H.
• Application Number:
  US07/890,043
• Time in Patent Office: 559 Days
• Field of Search: 331/1 A, 331/17, 331/16, 331/25
• US Class Current: 331/16
• CPC Class Codes: H03L 7/093 using special filtering or amplification characteristics in the loop H03L7/087 - H03L7/091 take precedence
• CPC Class Codes: H03L 7/107 using a variable transfer function for the loop, e.g. low pass filter having a variable bandwidth

Abstract

A self-adjusting phase-locked loop (PLL) parameter adjusting device (APAD) (100) and method that automatically adjusts a phase-locked loop to provide tracking ability when and where needed, as opposed to utilizing a PLL adjusting device with preset parameters, thus maintaining minimal possible noise bandwidth. The method utilizes (1) successively integrating the PLL error output signal over a number of samples to provide a plurality of sums, (2) checking a predetermined number of sums and recording and counting the sign of each sum, (3) comparing the counted record to a predetermined threshold value, and (4) automatically adjusting PLL parameter(s) and the sample number in accordance with a predetermined strategy, such that adjusted PLL parameters are provided to the PLL.

Claims

1. An automatic phase-locked loop (PLL) parameter adjusting device having a PLL error signal input, comprising:

(A) integrating means (I), having an I input and an I output, the I input being operably coupled to receive the PLL error signal, for successively integrating the PLL error over a predetermined N sample interval and providing a sum signal at the I output, where N is a first preselected integer, and further being operably coupled to receive an output signal from an automatic decision means, for adjusting N in correspondence with said output signal,

(B) a counting means (C), having a C input and a C output, being operably coupled to receive the I output signal, for counting K sum signals (where K is a second preselected integer) and recording and counting the sign of said signals to provide a counter comparator signal at the C output,

(C) a threshold means (TH), having a TH input and a TH output, the TH input being operably coupled to receive the C output (counter comparator) signal, for comparing the C output (counter comparator) signal with a predetermined threshold value to provide a parameter modifications signal at the TH output, and

(D) the automatic decision means (AD), having an AD input and at least first and second AD outputs, being operably coupled to receive the TH output signal, for;

(D1) adjusting N in accordance with a predetermined strategy and providing a first AD output signal representing the adjustment of N to the integrating means, and

(D2) adjusting PLL parameter(s) in accordance with the predetermined strategy and providing AD output signal(s) that represent(s) the adjusted PLL parameter(s), being at least a second AD output signal, to the PLL.

2. The device of claim 1 wherein the integrating means consists of one of:

(A) a first integrator, operably coupled to receive the PLL error signal, the first integrator comprising a first summer and a first delay means that receives input from an output of the first summer and from a first counter, wherein the first counter is operably coupled to the AD, to the delay means, and to a first switch such that the first counter causes the first switch to close after every N samples are summed to provide the I output signal and increments/decrements N in accordance with an output signal from the AD, and

(B) a predetermined op-amp, operably coupled to receive the PLL error signal, having a switch and a predetermined capacitor coupled in parallel to an input and an output of the op-amp, the switch being further coupled to the AD for resetting, the output of the op-amp being further coupled to a sample and hold circuit that is coupled to a first timer that periodically receives an output signal from the AD and increments/decrements N in response thereto, such that the sample and hold circuit provides the I output signal.

3. The device of claim 1 wherein the counting means consists of one of:

(A) a hard-limiting limiter circuit, operably coupled to receive the I output signal, for providing a limiter output signal to a second integrator, a second integrator, operably coupled to receive the limiter output signal, the second integrator comprising a second summer and a second delay means that receives input from an output of the second summer and from a second counter, wherein the second counter is operably coupled to the second delay means and to a second switch such that the second counter causes the second switch to close after every K events to provide the C output signal, and

(B) a hard-limiting limiter circuit, operably coupled to receive the I output signal, for providing a limiter output signal to a counter that is operably coupled to the TH, such that the counter provides the C output signal after every K events, while the counter is periodically reset by AD.

4. The device of claim 1 wherein the threshold means is a hard-limiting limiter circuit, operably coupled to receive the C output signal, that provides a predetermined threshold value, ±

T, for comparison with the counter comparison signal.

5. The device of claim 1 wherein the predetermined strategy provides for:

(A) where the counter comparator signal is greater than or equal to a predetermined threshold value and N is greater than a preselected minimum value, the AD;

(A1) provides an output AD signal to the integrating means for decrementing N by 1/c times a range of N, where c is a predetermined value and the range of N is predetermined, and

(A2) where a range of PLL parameter adjustment is less than a predetermined value, adjusts the PLL parameter(s) by a increment step to provide an accelerated PLL tracking speed, and

(B) where the counter comparator signal is less than the predetermined value and N is less than a preselected minimum value, the AD;

(B1) provides an output AD signal to the integrating means for incrementing N by 1/d times the range of N, where d is a predetermined value and the range of N is predetermined, and

(B2) where the range of PLL parameter adjustment is greater than a predetermined value, adjusts the PLL parameter(s) by a decrement step to provide a decelerated PLL tracking speed.

6. The device of claim 5 the AD further including:

wherein a first PLL parameter is adjusted;

(A) for the increment step of (A2), means for incrementing the first PLL parameter by (1/a) times the range to provide an adjusted first parameter, where a is a first preselected value,

(B) for the decrement step of (B2), means for decrementing the first PLL parameter by (1/b) times the range to provide an adjusted first parameter, where b is a second preselected value, and

wherein a second PLL parameter is adjusted;

means for squaring the value of the adjusted first PLL parameter and means for dividing the squared value by a third preselected value to provide the adjusted second PLL parameter.

7. The device of claim 6 wherein at least one of the following relationships is selected:

(A) a is different from b; and

(B) c is different from d.

8. The device of claim 1 further including a phase locked-loop (PLL), operably coupled to receive an input signal, for providing the PLL error signal and for utilizing at least a AD output signal(s) that represent(s) the adjusted PLL parameter(s).

9. A system for regulating a voltage-controlled oscillator with an automatically adjusted phase-locked loop (PLL), the PLL having an input signal, comprising:

(A) a PLL, having at least first and second PLL inputs and at least first and second PLL outputs, operably coupled to receive the input signal at the first PLL input, for providing a PLL error signal to an automatic PLL parameter adjusting unit as a first PLL output signal, receiving and utilizing adjusted PLL parameter(s) to provide an adjusted PLL signal to a voltage-controlled oscillator (VCO) means at the second PLL output.

(B) the automatic PLL parameter adjusting unit (APA), having predetermined PLL parameters and having a first APA input and at least a first APA output, operably coupled to receive the PLL error signal at the first APA input, for automatically adjusting the predetermined PLL parameters in accordance with a predetermined strategy and providing signal(s) representing the adjusted PLL parameter(s) at APA output(s) that are operably coupled to PLL input(s), and

(C) the voltage-controlled oscillator (VCO) means, having at least a first VCO input and a first VCO output, operably coupled to receive the adjusted PLL signal at the first VCO input, for tuning the VCO in accordance with a predetermined scheme to provide the first VCO output signal, wherein the automatic phase-locked loop (PLL) parameter adjusting unit that utilizes a PLL error signal, comprises;

(A) integrating means (I), having an I input and an I output, the I input being operably coupled to receive the PLL error signal, for successively integrating the PLL error for a predetermined N sample interval and providing a sum signal at the I output, where N is a first preselected integer,

(B) a counting means (C), having a C input and a C output, being operably coupled to receive the I output signal, for counting K sum signals (where K is a second preselected integer) and recording and counting the sign of said signals to provide a counter comparator signal at the C output,

(C) a threshold means (TH), having a TH input and a TH output, the TH input being operably coupled to receive the C output (counter comparator) signal, for comparing the C output (counter comparator) signal with a predetermined threshold value to provide a parameter modification signal at the TH output, and

(D) an automatic decision means (AD), having a AD input and at least first and second AD outputs, being operably coupled to receive the TH output signal, for;

(D1) adjusting N in accordance with a predetermined strategy and providing a first AD output signal representing the adjustment of N to the integrating means, and

(D2) adjusting PLL parameter(s) in accordance with the predetermined strategy and providing AD output signal(s) that represent(s) the adjusted PLL parameter(s), being at least a second AD output signal, to the PLL.

10. The system of claim 9 wherein the integrating means consists of one of:

(A) a first integrator, operably coupled to receive the PLL error signal, the first integrator comprising a first summer and a first delay means that receives input from an output of the first summer and from a first counter, wherein the first counter is operably coupled to the AD, to the delay means, and to a first switch such that the first counter causes the first switch to close after every N samples are summed to provide the I output signal and increments/decrements N in accordance with an output signal from the AD, and

(B) a predetermined op-amp, operably coupled to receive the PLL error signal, having a switch and a predetermined capacitor coupled in parallel to an input and an output of the op-amp, the switch being further coupled to the AD for resetting, the output of the op-amp being further coupled to a sample and hold circuit that is coupled to a first timer that periodically receives an output signal from the AD and increments/decrements N in response thereto, such that the sample and hold circuit provides the I output signal.

11. The system of claim 9 wherein the counting means consists of one of:

(A) a hard-limiting limiter circuit, operably coupled to receive the I output signal, for providing a limiter output signal to a second integrator, a second integrator, operably coupled to receive the limiter output signal, the second integrator comprising a second summer and a second delay means that receives input from an output of the second summer and from a second counter, wherein the second counter is operably coupled to the second delay means and to a second switch such that the second counter causes the second switch to close after every K events to provide the C output signal, and

(B) a hard-limiting limiter circuit, operably coupled to receive the I output signal, for providing a limiter output signal to a counter that is operably coupled to the TH, such that the counter provides the C output signal after every K events, while the counter is periodically reset by AD.

12. The system of claim 9 wherein the threshold means is a hard-limiting limiter circuit, operably coupled to receive the C output signal, that provides a predetermined threshold value, ±

T, for comparison with the counter comparison signal.

13. The system of claim 9 wherein the predetermined strategy provides for:

(A) where the counter comparator signal is greater than or equal to a predetermined threshold value and N is greater than a preselected minimum value, the AD;

(A1) provides an output AD signal to the integrating means for decrementing N by 1/c times a range of N, where c is a predetermined value and the range of N is predetermined, and

(A2) where a range of PLL parameter adjustment is less than a predetermined value, adjusts the PLL parameter(s) by a increment step to provide an accelerated PLL tracking speed, and

(B) where the counter comparator signal is less than the predetermined threshold value and N is less than a preselected minimum value, the AD;

(B1) provides an output AD signal to the integrating means for incrementing N by 1/d times a range of N, where d is a predetermined value and the range of N is predetermined, and

(B2) where the range of PLL parameter adjustment is greater than a predetermined value, adjusts the PLL parameter(s) by a decrement step to provide a decelerated PLL tracking speed.

14. The system of claim 13 wherein the AD further includes:

wherein a first PLL parameter is adjusted;

(A) for the increment step of (A2), means for incrementing the first PLL parameter by (1/a) times the range to provide an adjusted first parameter, where a is a first preselected value,

(B) for the decrement step of (B2), means for decrementing the first PLL parameter by (1/b) times the range to provide an adjusted first parameter, where b is a second preselected value, and

wherein a second PLL parameter is adjusted;

means for squaring the value of the adjusted first PLL parameter and means for dividing the squared value by a third preselected value to provide the adjusted second PLL parameter.

15. The system of claim 14 wherein at least one of the following relationships is selected:

(A) a is different from b; and

(B) c is different from d.

16. A method for automatically adjusting parameters of a phase-locked loop (PLL) that has a PLL error output signal, comprising the steps of:

(A) successively integrating the PLL error output signal over N samples to provide a sum, where N, is a first preselected integer, to provide a plurality of sums,

(B) checking K sums, where K is a second preselected integer, and recording and counting the sign of each sum,

(C) comparing the counted record to a predetermined threshold value, and

(D) automatically adjusting PLL parameter(s) and N in accordance with a predetermined strategy based on the comparison, such that adjusted PLL parameters are provided to the PLL.

17. The method of claim 16 wherein the predetermined strategy includes the steps of:

(A) where the counter comparator signal is greater than or equal to a predetermined threshold value and N is greater than a preselected minimum value;

(A1) causing N to be decremented by 1/c times a range of N, where c is a predetermined value and the range of N is predetermined, and

(A2) where a range of PLL parameter adjustment is less than a predetermined value, adjusting the PLL parameter(s) by a increment step to provide an accelerated PLL tracking speed, and

(B) where the counter comparator signal is less than the predetermined threshold value and N is less than a preselected minimum value;

(B1) causing N to be incremented by 1/d times a range of N, where d is a predetermined value and the range of N is predetermined, and

(B2) where the range of PLL parameter adjustment is greater than a predetermined value, adjusting the PLL parameter(s) by a decrement step to provide a decelerated PLL tracking speed.

18. The method of claim 17 further including the steps of:

for adjusting a first PLL parameter;

(A) for an increment step of (A2), incrementing the first PLL parameter by (1/a) times the range to provide an adjusted first parameter, where a is a first preselected value,

(B) for a decrement step of (B2), decrementing the first PLL parameter by (1/b) times the range to provide an adjusted first parameter, where b is a second preselected value, and

for adjusting a second PLL parameter;

squaring the value of the adjusted first PLL parameter and dividing the squared value by a third preselected value to provide the adjusted second PLL parameter.

19. The method of claim 18 wherein at least one of the following relationships is selected:

(A) a is different from b; and

(B) c is different from d.

20. The method of claim 16 wherein the phase locked-loop (PLL) being adjusted is operably coupled to a voltage-controlled oscillator, for controlling the output of the voltage-controlled oscillator.