Frequency generator and associated method

Patent metadata

Field	Value
Publication number	US-10771072-B2
Application number	US-201916691016-A
Country	US
Kind code	B2
Filing date	Nov 21, 2019
Priority date	Aug 29, 2017
Publication date	Sep 8, 2020
Grant date	Sep 8, 2020

Abstract

A frequency generator is disclosed. The frequency generator is for generating an oscillator clock according to a reference clock, and the frequency generator is used in a frequency hopping system that switches a carrier frequency among a plurality of channels, and the carrier frequency further carries a modulation frequency for data transmission. The frequency generator includes: a frequency hopping and modulation control unit, arranged for generating a current channel according to a channel hopping sequence and a frequency command word (FCW) based on the reference clock, a digital-controlled oscillator (DCO), arranged for to generating the oscillator clock according to an oscillator tuning word (OTW) obtained according to the estimated DCO normalization value. An associated method is also disclosed.

First claim

What is claimed is:

1. A frequency generator for generating an oscillator clock according to a reference clock, the frequency generator being used in a frequency hopping system that switches a carrier frequency among a plurality of channels, the carrier frequency further carrying a modulation frequency for data transmission, the frequency generator comprising:
a frequency hopping and modulation control unit, arranged for generating a current channel according to a channel hopping sequence and a frequency command word (FCW) based on the reference clock, wherein the FCW includes:
a calibration unit, arranged for iteratively calibrating an estimated DCO normalization value during frequency hopping according to the current channel and a phase error obtained according to the oscillator clock and the reference clock; and
a digital-controlled oscillator (DCO), arranged for to generating the oscillator clock according to an oscillator tuning word (OTW) obtained according to the estimated DCO normalization value.

2. The frequency generator of claim 1 , wherein the estimated DCO normalization value is a function of a frequency of the reference clock over a DCO gain.

3. The frequency generator of claim 2 , wherein the DCO gain is a function of a frequency of the oscillator clock over the OTW.

4. The frequency generator of claim 1 , wherein the FCW is a function of a frequency of the oscillator clock over a frequency of the reference clock.

5. The frequency generator of claim 1 , wherein the FCW includes a first FCW component corresponding to a frequency of a predefined channel, and the predefined channel is a middle channel among the plurality of channels.

6. The frequency generator of claim 1 , wherein the calibration unit iteratively calibrates the estimated DCO normalization value during frequency hopping based on the LMS algorithm.

7. The frequency generator of claim 5 , wherein the OTW includes:
a first OTW component corresponding to the frequency of the predefined channel;
a second OTW component corresponding to a frequency difference between the predefined channel and the current channel; and
a third OTW component corresponding to the modulation frequency.

8. The frequency generator of claim 7 , wherein the FCW further includes a second FCW component corresponding to the frequency difference between the predefined channel and the current channel, and the frequency generator further comprises a first multiplier, arranged for multiplying the second FCW component by the estimated DCO normalization value to generate the second OTW component.

9. The frequency generator of claim 8 , wherein the FCW further includes a third FCW component corresponding to the modulation frequency, and the frequency generator further comprises a second multiplier, arranged for multiplying the third FCW component by the estimated DCO normalization value to generate the third OTW component.

10. The frequency generator of claim 9 , further comprising a third multiplier, arranged for multiplying the phase error by the estimated DCO normalization value to generate the third OTW component.

11. A frequency generator for generating an oscillator clock according to a reference clock, the frequency generator being used in a frequency hopping system that switches a carrier frequency among a plurality of channels, the carrier frequency further carrying a modulation frequency for data transmission, the frequency generator comprising:
a frequency hopping and modulation control unit, arranged for generating a current channel according to a channel hopping sequence;
a calibration unit, arranged for sampling a phase error according to the reference clock, and iteratively calibrating an estimated DCO normalization value during frequency hopping according to the current channel and the phase error obtained according to the oscillator clock and the reference clock; and
a digital-controlled oscillator (DCO), arranged for to generating the oscillator clock according to an oscillator tuning word (OTW) obtained according to the estimated DCO normalization value.

12. The frequency generator of claim 11 , wherein the estimated DCO normalization value is a function of a frequency of the reference clock over a DCO gain.

13. The frequency generator of claim 12 , wherein the DCO gain is a function of a frequency of the oscillator clock over the OTW.

14. The frequency generator of claim 11 , wherein the calibration unit further obtains a difference by subtracting a predefined channel from the current channel, and extracts a sign of the difference.

15. The frequency generator of claim 14 , wherein the calibration unit further generates a gradient by multiplying the sign by the sampled phase error.

16. The frequency generator of claim 15 , wherein the calibration unit further generates the estimated DCO normalization value according to the gradient.

17. The frequency generator of claim 14 , wherein the predefined channel is a middle channel among the plurality of channels.

18. A frequency generation method for generating an oscillator clock according to a reference clock, the frequency generation method being used for a frequency hopping system that switches a carrier frequency among a plurality of channels, the carrier frequency further carrying a modulation frequency for data transmission, the method comprising:
obtaining a channel hopping sequence, wherein the channel hopping sequence indicates a sequence of change of a current channel among the plurality of channels of the frequency hopping system;
obtaining the current channel among the plurality of channels according to the channel hopping sequence; and
iteratively calibrating an estimated digital-controlled oscillator (DCO) normalization value during frequency hopping at least according to the current channel, wherein the estimated DCO normalization value is a function of a frequency of the reference clock over a DCO gain, and the DCO gain is a function of a frequency of the oscillator clock over an oscillator tuning word (OTW); and
generating the oscillator clock according to the estimated DCO normalization value.

19. The frequency generation method of claim 18 , further comprising:
generating a phase error according to the oscillator clock and the reference clock.

20. The frequency generation method of claim 19 , wherein the iteratively calibrating the estimated DCO normalization value during frequency hopping at least according to the current channel comprises:
iteratively calibrating the estimated DCO normalization value during frequency hopping at least according to the current channel and the phase error.

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Liao Chia-Chun
• Yuan Min-Shueh
• Li Chao-Chieh
• Staszewski Robert Bogdan

Classifications

• H03L7/16 Primary

  Indirect frequency synthesis, i.e. generating a desired one of a number of predetermined frequencies using a frequency- or phase-locked loop · CPC title

• H03L7/0992

  comprising a counter or a frequency divider · CPC title

• H03L7/093

  using special filtering or amplification characteristics in the loop (H03L7/087 - H03L7/091 take precedence) · CPC title

• H03C3/095

  applying frequency modulation to the loop in front of the voltage controlled oscillator · CPC title

• H03L2207/50

  All digital phase-locked loop · CPC title