Digital sinusoid generator

Patent metadata

Field	Value
Publication number	US-11092993-B2
Application number	US-201916437705-A
Country	US
Kind code	B2
Filing date	Jun 11, 2019
Priority date	Jun 18, 2018
Publication date	Aug 17, 2021
Grant date	Aug 17, 2021

Abstract

A recursive digital sinusoid generator generates recursive values used in the production of a digital sinusoid output. The recursive values are generated at a first frequency. A sinusoid value generator generates replacement values at a second frequency, wherein the second frequency is less than the first frequency. The generated recursive values are periodically replaced with the generated replacement values without interrupting production of the digital sinusoid output at the first frequency. This periodic replacement effectively corrects for a finite precision error which accumulates in the recursive values over time.

First claim

What is claimed is:

1. An apparatus, comprising:
a recursive digital sinusoid generator configured to generate one or more recursive values for producing a digital sinusoid output, the recursive values being generated at a first frequency;
a sinusoid value generator configured to generate one or more replacement values at a second frequency, wherein the second frequency is less than the first frequency; and
a control circuit configured to cause a periodic replacement of at least one of the generated recursive values with at least one of the generated replacement values without interrupting production of the digital sinusoid output at the first frequency.

2. The apparatus of claim 1 , wherein the recursive digital sinusoid generator initially produces the digital sinusoid output in response to a set of operating parameters, and wherein the sinusoid value generator is further configured to generate said set of operating parameters.

3. The apparatus of claim 2 , wherein the set of operating parameters includes one or more gain values.

4. The apparatus of claim 2 , wherein the set of operating parameters includes one or more initial condition values for said one or more recursive values.

5. The apparatus of claim 1 , wherein said one or more recursive values accumulate a finite precision error over time and the periodic replacement of at least one of the generated recursive values with at least one of the generated replacement values corrects for the accumulated finite precision error.

6. The apparatus of claim 1 , wherein the periodic replacement occurs once every few hundred times the one or more recursive values are generated.

7. The apparatus of claim 1 , wherein the periodic replacement occurs once every few thousand times the one or more recursive values are generated.

8. The apparatus of claim 1 , wherein the recursive digital sinusoid generator is a n-th order infinite impulse response (IIR) type digital filter configured by a set of operating parameters to generate the digital sinusoid output.

9. The apparatus of claim 8 , wherein the n-th order is a second order.

10. The apparatus of claim 8 , wherein the set of operating parameters includes a delay feedback gain value.

11. The apparatus of claim 8 , wherein the set of operating parameters includes initial condition values for the one or more recursive values.

12. The apparatus of claim 1 , wherein the sinusoid value generator comprises a coordinate rotation digital computer (CORDIC) configured to generate the replacement values for certain angles of a desired sinusoid.

13. The apparatus of claim 12 , wherein the certain angles are periodic angles.

14. The apparatus of claim 12 , wherein the control circuit causes at least one of the generated replacement values to replace at least one of the generated recursive values when an angle of the digital sinusoid output matches the certain angle at which the CORDIC generated the replacement values.

15. A method, comprising:
generating at a first frequency one or more recursive values for producing a digital sinusoid output;
generating at a second frequency one or more replacement values, wherein the second frequency is less than the first frequency; and
periodically replacing at least one of the generated recursive values with at least one of the generated replacement values without interrupting production of the digital sinusoid output at the first frequency.

16. The method of claim 15 , wherein said one or more recursive values accumulate a finite precision error over time and the periodic replacement of at least one of the generated recursive values with at least one of the generated replacement values corrects for the accumulated finite precision error.

17. The method of claim 15 , wherein the periodic replacement occurs once every few hundred times the one or more recursive values are generated.

18. The method of claim 15 , wherein the periodic replacement occurs once every few thousand times the one or more recursive values are generated.

19. The method of claim 15 , wherein the replacement values are generated for certain angles of a desired sinusoid.

20. The method of claim 19 , wherein the certain angles are periodic angles.

21. The method of claim 19 , wherein the at least one of the generated replacement values replaces at least one of the generated recursive values when an angle of the digital sinusoid output matches the certain angle for which the replacement values were generated.

Assignees

• St Microelectronics Int Nv

Inventors

• Bal Ankur
• Singh Rupesh

Classifications

• H03B28/00 Primary

  Generation of oscillations by methods not covered by groups H03B5/00 - H03B27/00, including modification of the waveform to produce sinusoidal oscillations (analogue function generators for performing computing operations G06G7/26; use of transformers for conversion of waveform in AC-AC converters H02M5/18) · CPC title

• G06F1/022 Primary

  Waveform generators, i.e. devices for generating periodical functions of time, e.g. direct digital synthesizers (G06F1/025, G06F1/03 take precedence) · CPC title

• H03K4/026

  using digital techniques · CPC title

• H03K3/80

  Generating trains of sinusoidal oscillations (by keying or interruption of sinusoidal oscillations H03C; for transmission of digital information H04L) · CPC title