Nyquist response restoring delta-sigma modulator based analog to digital and digital to analog conversion

• US 6,373,418 B1
• Filed: 05/25/2000
• Issued: 04/16/2002
• Est. Priority Date: 05/25/2000
• Status: Expired due to Term

• Current Assignee: Rockwell Collins, Inc. (Rtx Corporation)
• Original Assignee: Rockwell Collins, Inc. (Rtx Corporation)
• Inventors: Abbey, Duane L.
• Primary Examiner(s): JEAN PIERRE, PEGUY
• Application Number:
  US09/579,025
• Time in Patent Office: 691 Days
• Field of Search: 341/143, 341/144, 341/155
• US Class Current: 341/143
• CPC Class Codes: H03M 3/416 all these quantisers being multiple bit quantisers
• CPC Class Codes: H03M 7/3022 having multiple quantisers arranged in cascaded loops, each of the second and further loops processing the quantisation error of the loop preceding it, i.e. multiple stage noise shaping [MASH] type

Abstract

A high pass delta-sigma modulator apparatus is disclosed for use in analog-to-digital and digital-to-analog converters. The apparatus includes a signal input, a differentiator component, a signal transducer producing an output signal, an inverse signal transducer producing an input compatible feedback signal, and a feedback loop coupling a feedback signal back to said differentiator component. Also disclosed is a Nyquist response restoring delta-sigma modulator based analog-to-digital and digital-to-analog converter apparatus having a first modulator set, a first scaling component, a second modulator set and a post processing combiner. In the various embodiments, the modulator sets can include an analog signal input, a digital signal input, a quantizer, a digital resolution rounder, a digital resolution truncator, a digital-to-analog signal transducer, a digital resolution expander, a delta sigma modulator structure, a feedback structure, an analog signal output, and one or more digital signal outputs.

Claims

1. A high pass delta-sigma modulator based signal converter apparatus, comprising:

a differentiator component, comprising a differentiator component input and a differentiator component output;

a signal transducer, comprising a signal transducer input and a signal transducer output, said signal transducer input coupled with said differentiator component output;

a summer component, coupled between said differentiator component output and said signal transducer input; and

an inverse signal transducer, comprising an inverse signal transducer input and an inverse signal transducer output, said inverse signal transducer input coupled with said signal transducer output, said inverse signal transducer output coupled with said summer component;

wherein said inverse signal transducer is part of a feedback loop coupling output from said signal transducer back to said summer component.

2. The high pass delta-sigma modulator based signal converter apparatus according to claim 1, further comprising:

a gain element coupled between said inverse signal transducer and said summer component; and

an output signal delay structure coupled between said signal transducer and said inverse signal transducer.

3. The high pass delta-sigma modulator based signal converter apparatus according to claim 2, wherein said differentiator component further comprises a differentiator stage, said differentiator stage comprising:

a differentiator stage delay structure comprising a differentiator stage delay structure input and a differentiator stage delay structure output, said differentiator stage delay structure input coupled with said differentiator component input;

a differentiator stage calibration component, comprising a differentiator stage calibration component input and a differentiator stage calibration component output, said differentiator stage calibration component input coupled with differentiator stage delay structure output; and

a differentiator stage subtractor, comprising a differentiator stage subtractor first input, a differentiator stage subtractor second input, and a differentiator stage subtractor output, said differentiator stage subtractor first input coupled with said differentiator component input, said differentiator stage subtractor second input coupled with said differentiator stage calibration component output, and said differentiator stage subtractor output coupled with said summer component;

wherein signals received by said differentiator stage subtractor first input are added, and signals received by said differentiator stage subtractor second input are subtracted by said differentiator stage subtractor.

4. The high pass delta-sigma modulator based signal converter apparatus according to claim 3, wherein said differentiator component comprises a plurality of cascaded differentiator and summer combination stages, each said differentiator stage comprising a respective gain component, a respective delay component, and a respective subtractor component, each said summer stage coupled with said inverse signal transducer via its said respective gain component.

5. The high pass delta-sigma modulator based signal converter apparatus according to claim 3, wherein said differentiator component is capable of receiving an analog input signal via said differentiator component input, wherein said signal transducer comprises an analog-to-digital quantizer;

and wherein said inverse signal transducer comprises a digital-to-analog converter.

6. The high pass delta-sigma modulator based signal converter apparatus according to claim 5, further comprising an output signal delay structure coupled with said signal transducer, said output signal delay structure comprising a first clock-phase digital latch component coupled with said signal transducer output, and a second clock-phase digital latch component coupled between said first clock-phase digital latch component and said inverse signal transducer;

and

said differentiator stage delay structure further comprising a first clock-phase sample-and-hold component coupled with said differentiator component input, and a second clock-phase sample-and-hold component coupled between said first clock-phase sample-and-hold component and said differentiator stage calibration component.

7. The high pass delta-sigma modulator based signal converter apparatus according to claim 5, further comprising a demultiplexer coupled to said analog-to-digital quantizer.

8. The high pass delta-sigma modulator based signal converter apparatus according to claim 3, wherein said differentiator component is capable of receiving a digital input signal via said differentiator component input, wherein said signal transducer comprises a digital resolution reducer, and wherein said inverse signal transducer comprises a digital resolution expander.

9. The high pass delta-sigma modulator based signal converter apparatus according to claim 8, further comprising an output signal delay structure coupled with said signal transducer, said output signal delay structure comprising a first clock-phase digital latch component coupled with said signal transducer output and a second clock-phase digital latch component coupled between said first clock-phase digital latch component and said inverse signal transducer;

and

said differentiator stage delay structure further comprising a first clock-phase digital latch component coupled with said differentiator component input, and a second clock-phase digital latch component coupled between said first clock-phase digital latch component and said differentiator stage calibration component.

10. The high pass delta-sigma modulator based signal converter apparatus according to claim 8, further comprising a demultiplexer coupled with said signal transducer.

11. The high pass delta-sigma modulator based signal converter apparatus according to claim 3, wherein said differentiator component is capable of receiving a digital input signal via said differentiator component input, wherein said signal transducer comprises a digital-to-analog transducer, and wherein said inverse signal transducer comprises an analog-to-digital converter.

12. The high pass delta-sigma modulator based signal converter apparatus according to claim 11, further comprising an output signal delay structure coupled with said signal transducer, said output signal delay structure comprising a first clock-phase sample-and-hold component coupled with said signal transducer output, and a second clock-phase sample-and-hold component coupled between said first clock-phase sample-and-hold component and said inverse signal transducer;

and

said differentiator stage delay structure further comprising a first clock-phase digital latch component coupled with said differentiator component input, and a second clock-phase digital latch component coupled between said first clock-phase digital latch component and said differentiator stage calibration component.

13. A delta-sigma modulator based converter apparatus, comprising:

a first low pass modulator set, comprising;

a first signal transducer, comprising a first signal transducer input and a first signal transducer output,

a first delta-sigma modulator structure, comprising a first delta-sigma modulator structure input and a first delta-sigma modulator structure output, said first delta-sigma modulator structure output coupled with said first signal transducer input,

a first inverse signal transducer, comprising a first inverse signal transducer input and a first inverse signal transducer output, said first inverse signal transducer input coupled with said first signal transducer output, said first inverse signal transducer output coupled with said first delta-sigma modulator structure, wherein said first inverse signal transducer is part of a feedback loop coupling output from said first signal transducer back to said first delta-sigma modulator structure, and

a first noise signal generation component, comprising a first noise signal generation component first input, a first noise signal generation component second input, and a first noise signal generation component output, said first noise signal generation component first input coupled with said first inverse signal transducer output, said first noise signal generation component second input coupled with said first delta-sigma modulator structure output, wherein signals received via said first noise signal generation component first input are subtracted from signals received via said first noise signal generation component second input and resultant signals are transmitted via said first noise signal generation component output;

a first scaling component, comprising a first scaling component input and a first scaling component output, said first scaling component input coupled with said first noise signal generation component output; and

a high pass modulator set, comprising;

a second signal transducer, comprising a second signal transducer input and a second signal transducer output,

a second delta-sigma modulator structure, comprising a second delta-sigma modulator structure input and a second delta-sigma modulator structure output, said second delta-sigma modulator structure input coupled with said first scaling component output, and said second delta-sigma modulator structure output coupled with said second signal transducer input, and

a second inverse signal transducer, comprising a second inverse signal transducer input and a second inverse signal transducer output, said second inverse signal transducer input coupled with said second signal transducer output, said second inverse signal transducer output coupled with said second delta-sigma modulator structure, wherein said second inverse signal transducer is part of a feedback loop coupling output from said second signal transducer back to said second delta-sigma modulator structure.

14. The delta-sigma modulator based converter apparatus according to claim 13, further comprising a plurality of modulator sets, said plurality of modulator sets comprising alternating low pass and high pass modulator sets.

15. The delta-sigma modulator based converter apparatus according to claim 13, wherein said first delta-sigma modulator structure is capable of receiving an analog input signal via said first delta-sigma modulator structure input, said first signal transducer comprises a first analog-to-digital quantizer, and said first inverse signal transducer comprises a first digital-to-analog converter;

and

wherein said second delta-sigma modulator structure is capable of receiving an analog input signal via said second delta-sigma modulator structure input, said second signal transducer comprises a second analog-to-digital quantizer, and said second inverse signal transducer comprises a second digital-to-analog converter.

16. The delta-sigma modulator based converter apparatus according to claim 15, further comprising a digital post processing structure, comprising a post processing structure first input and a post processing structure second input, said post processing structure first input coupled with said first signal transducer output and said post processing structure second input coupled with said second signal transducer output, said digital post processing structure further comprising a post processing structure output.

17. The delta-sigma modulator based converter apparatus according to claim 13, further comprising:

a second noise signal generation component, comprising a second noise signal generation component first input, a second noise signal generation component second input, and a second noise signal generation component output, said second noise signal generation component first input coupled with said second inverse signal transducer output, said second noise signal generation component second input coupled with said second delta-sigma modulator structure output, wherein signals received via said second noise signal generation component first input are subtracted from signals received via said second noise signal generation component second input and resultant signals are transmitted via said second noise signal generation component output;

a second scaling component, comprising a second scaling component input and a second scaling component output, said second scaling component input coupled with said second noise signal generation component output; and

a second low pass modulator set, comprising;

a third signal transducer, comprising a third signal transducer input and a third signal transducer output,

a third delta-sigma modulator structure, comprising a third delta-sigma modulator structure input and a third delta-sigma modulator structure output, said third delta-sigma modulator structure input coupled with said second scaling component output, and said third delta-sigma modulator structure output coupled with said third signal transducer input, and

a third inverse signal transducer, comprising a third inverse signal transducer input and a third inverse signal transducer output, said third inverse signal transducer input coupled with said third signal transducer output, said third inverse signal transducer output coupled with said third delta-sigma modulator structure, wherein said third inverse signal transducer is part of a feedback loop coupling output from said third signal transducer back to said third delta-sigma modulator structure.

18. The delta-sigma modulator based converter apparatus according to claim 17, wherein said first delta-sigma modulator structure is capable of receiving an analog input signal via said first delta-sigma modulator structure input, said first signal transducer comprises a first analog-to-digital quantizer, said first inverse signal transducer comprises a first digital-to-analog converter;

wherein said second delta-sigma modulator structure is capable of receiving an analog input signal via said second delta-sigma modulator structure input, said second signal transducer comprises a second analog-to-digital quantizer, and said second inverse signal transducer comprises a second digital-to-analog converter; and

wherein said third delta-sigma modulator structure is capable of receiving an analog input signal via said third delta-sigma modulator structure input, said third signal transducer comprises a third analog-to-digital quantizer, and said third inverse signal transducer comprises a third digital-to-analog converter.

19. The delta-sigma modulator based converter apparatus according to claim 18, further comprising a digital post processing structure, comprising a post processing structure first input, a post processing structure second input and a post processing structure third input, said post processing structure first input coupled with said first signal transducer output, said post processing structure second input coupled with said second signal transducer output, and said post processing structure third input coupled with said third signal transducer output, said digital post processing structure further comprising a post processing structure output.

20. The delta-sigma modulator based converter apparatus according to claim 17, wherein said first delta-sigma modulator structure component is capable of receiving a digital input signal via said first delta-sigma modulator structure component input, wherein said first signal transducer comprises a first digital resolution reducer, wherein said second signal transducer comprises a second digital resolution reducer, wherein said third signal transducer comprises a third digital resolution reducer, wherein said first inverse signal transducer comprises a first digital resolution expander, wherein said second inverse signal transducer comprises a second digital resolution expander, and wherein said third inverse signal transducer comprises a third digital resolution expander.

21. The delta-sigma modulator based converter apparatus according to claim 20, further comprising a digital post processing structure, comprising a post processing structure first input, a post processing structure second input, and a post processing structure third input, said post processing structure first input coupled with said first signal transducer output, said post processing structure second input coupled with said second signal transducer output, and said post processing structure third input coupled with said third signal transducer output, said digital post processing structure further comprising a post processing structure output.

22. The delta-sigma modulator based converter apparatus according to claim 20, further comprising:

a first digital post processing structure, comprising a first digital post processing structure input and a first digital post processing structure output, said first digital post processing structure input coupled with said first signal transducer output;

a second digital post processing structure, comprising a second digital post processing structure input and a second digital post processing structure output, said second digital post processing structure input coupled with said second signal transducer output;

a third digital post processing structure, comprising a third digital post processing structure input and a third digital post processing structure output, said third digital post processing structure input coupled with said third signal transducer output;

a first digital-to-analog converter, comprising a first digital-to-analog converter input and a first digital-to-analog converter output, said first digital-to-analog converter input coupled with said first digital post processing structure output;

a second digital-to-analog converter, comprising a second digital-to-analog converter input and a second digital-to-analog converter output, said second digital-to-analog converter input coupled with said second digital post processing structure output;

a third digital-to-analog converter, comprising a third digital-to-analog converter input and a third digital-to-analog converter output, said third digital-to-analog converter input coupled with said third digital post processing structure output;

a first gain adjustment component, comprising a first gain adjustment component input and a first gain adjustment component output, said first gain adjustment component input coupled with said first digital-to-analog converter output;

a second gain adjustment component, comprising a second gain adjustment component input and a second gain adjustment component output, said second gain adjustment component input coupled with said second digital-to-analog converter output; and

a third gain adjustment component, comprising a third gain adjustment component input and a third gain adjustment component output, said third gain adjustment component input coupled with said third digital-to-analog converter output; and

a combiner, comprising a combiner first input, a combiner second input, a combiner third input and a combiner output, said combiner first input coupled with said first gain adjustment component output, said combiner second input coupled with said second gain adjustment component output and said combiner third input coupled with said third gain adjustment component output.

23. The delta-sigma modulator based converter apparatus according to claim 13, wherein said first delta-sigma modulator structure component is capable of receiving a digital input signal via said first delta-sigma modulator structure component input, wherein said first signal transducer comprises a first digital resolution reducer, wherein said second signal transducer comprises a second digital resolution reducer, wherein said first inverse signal transducer comprises a first digital resolution expander, and wherein said second inverse signal transducer comprises a second digital resolution expander.

24. The delta-sigma modulator based converter apparatus according to claim 23, further comprising a digital post processing structure, comprising a post processing structure first input and a post processing structure second input, said post processing structure first input coupled with said first signal transducer output and said post processing structure second input coupled with said second signal transducer output, said digital post processing structure further comprising a post processing structure output.

25. The delta-sigma modulator based converter apparatus according to claim 23, further comprising:

a first digital post processing structure, comprising a first digital post processing structure input and a first digital post processing structure output, said first digital post processing structure input coupled with said first signal transducer output;

a second digital post processing structure, comprising a second digital post processing structure input and a second digital post processing structure output, said second digital post processing structure input coupled with said second signal transducer output;

a first digital-to-analog converter, comprising a first digital-to-analog converter input and a first digital-to-analog converter output, said first digital-to-analog converter input coupled with said first digital post processing structure output;

a second digital-to-analog converter, comprising a second digital-to-analog converter input and a second digital-to-analog converter output, said second digital-to-analog converter input coupled with said second digital post processing structure output;

a first gain adjustment component, comprising a first gain adjustment component input and a first gain adjustment component output, said first gain adjustment component input coupled with said first digital-to-analog converter output;

a second gain adjustment component, comprising a second gain adjustment component input and a second gain adjustment component output, said second gain adjustment component input coupled with said second digital-to-analog converter output; and

a combiner, comprising a combiner first input, a combiner second input and a combiner output, said combiner first input coupled with said first gain adjustment component output, and said combiner second input coupled with said second gain adjustment component output.

26. A method for processing an analog signal and outputting a digital signal, comprising the steps of:

inputting an analog signal into a differentiator component of a high pass modulator set;

processing the analog signal by passing it through at least one differentiator component followed by a summer component;

transferring the processed analog signal from said summer component to a signal transducer;

converting the processed analog signal into a transducer processed digital signal;

re-converting the transducer processed digital signal to an analog feedback signal;

feeding the analog feedback signal back to the summer component; and

outputting the transducer processed digital signal from the high pass modulator set.

27. The method of claim 26, wherein said processing step comprises passing the analog signal through a plurality of cascaded differentiator stages and through a summer located after each differentiator stage in the cascade.

28. The method of claim 27, further comprising the steps of:

adjusting the gain of the analog feedback signal before feeding it back; and

summing, after each differentiator stage, the analog signal with the gain adjusted analog feedback signal.

29. A signal converter apparatus, comprising:

first low pass modulator set means for filtering an input signal and outputting a first noise signal and a first data signal;

first scaling component means for scaling the first noise signal and outputting a scaled first noise signal; and

high pass modulator set means for filtering the scaled first noise signal and outputting a second noise signal and a second data signal.

30. The converter apparatus of claim 29, further comprising:

second scaling component means for scaling the second noise signal and outputting a scaled second noise signal;

second low pass modulator set means for filtering the scaled second noise signal and outputting a third noise signal and a third data signal;

digital post processing means for processing the second data signal and the third data signal;

first combiner means for combining the first data signal and the second data signal and for outputting a first combined signal; and

second combiner means for combining the first combined signal and the third data signal and for outputting a second combined signal.