Method and apparatus for spectrum spreading of a pulse-density modulated waveform

Patent metadata

Field	Value
Publication number	US-10148473-B2
Application number	US-201815860016-A
Country	US
Kind code	B2
Filing date	Jan 2, 2018
Priority date	Apr 11, 2014
Publication date	Dec 4, 2018
Grant date	Dec 4, 2018

Abstract

Methods and systems are provided for spreading spectral density of digital-to-analog conversion output signals. A spreading circuit may spread a digital-to-analog converter (DAC) output signal over a particular frequency spectrum, with the spreading circuit receiving the DAC output signal; generating a plurality of internal control signals; and generating based on the DAC output signal and the one or more internal control signal a corresponding spread output signal. The Internal control signals may comprise at least a first control signal, generated based on sequences meeting at least one particular criterion, a second control signal, generated based on a feedback corresponding to an intermediate output generated within the spreading circuit. The spreading circuit may generate the first control signal based on zero-sum sequences. The spreading circuit may generate a stream of pulses based on the intermediate output, and may generate the feedback signal based on the stream of pulses.

First claim

What is claimed is:

1. A system comprising:
a digital-to-analog converter (DAC) circuit that generates an output signal; and
a spreading circuit that spreads the DAC output signal over a particular frequency spectrum, wherein the spreading circuit:
receives the DAC output signal;
generates a plurality of internal control signals, wherein;
the spreading circuit generates at least a first control signal based on sequences meeting at least one particular criterion; and
the spreading circuit generates a second control signal based on a feedback corresponding to an intermediate output generated within the spreading circuit; and

generates based on the DAC output signal and the plurality of internal control signals, a corresponding spread output signal.

2. The system of claim 1 , wherein generating the second control signal comprises applying an adjustment to the intermediate output.

3. The system of claim 1 , wherein the spreading circuit sets the second control signal based on applying of inversion to the intermediate output.

4. The system of claim 1 , wherein the spreading circuit generates a stream of pulses based on the intermediate output; and generates the feedback signal based on the stream of pulses.

5. The system of claim 4 , wherein the spreading circuit sets a number of pulses in the stream of pulses to equal to a number of pulses in the DAC output signal.

6. The system of claim 4 , wherein the spreading circuit sets the second control signal based on comparing of a value corresponding to the intermediate output with a pre-defined value.

7. The system of claim 1 , wherein generating the second control signal comprises applying a delay.

8. The system of claim 7 , wherein applying the delay is synchronized to the generating of the first control signal.

9. The system of claim 8 , wherein applying the delay and generating the first control signal are synchronized to the DAC output signal.

10. The system of claim 1 , wherein the spreading circuit generates the first control signal based on zero-sum sequences.

11. The system of claim 10 , wherein the zero-sum sequences comprise sequences of 1s and −1s, each zero-sum sequence having an equal number of 1s and −1s.

12. The system of claim 10 , wherein the zero-sum sequences comprise four bit long sequences.

13. The system of claim 1 , wherein the spreading circuit generates the first control signal based on randomly generated number.

14. The system of claim 13 , wherein the spreading circuit generates the randomly generated number based on linear feedback shifting.

15. The system of claim 13 , wherein generating the first control signal is synchronized to the DAC output signal and generating the randomly number is synchronized to a clock set based on a frequency of the DAC output signal.

Assignees

• Entropic Communications Llc

Inventors

• Petrovic Branislav
• Alelyunas Carl Harry

Classifications

• H04B1/692

  Hybrid techniques using combinations of two or more spread spectrum techniques · CPC title

• H04B1/71632

  Signal aspects (H04B1/7172 and H04B1/7176 take precedence) · CPC title

• H04B1/7172

  Pulse shape (in general H04L25/03834) · CPC title

• H04L27/04

  Modulator circuits; Transmitter circuits · CPC title

• H04B1/707

  using direct sequence modulation · CPC title