Multiphase, interleaved direct digital synthesis methods and structures

A method of generating a periodic stream of digital words that occur at a clock frequency fclk and represent respective amplitudes of a predetermined periodic waveform wherein said periodic stream has a period P and said digital words are spaced by a phase step φs that is a portion of said period, the method comprising the steps of:

• with a count capacity C, counting modulo nφs at a reduced clock frequency (1/n)fclk to thereby generate a primary substream of digital words;
• phase offsetting said primary substream to form n−1 secondary substreams of digital words wherein said primary and secondary substreams are phase spaced by said phase step φs;
• converting the digital words of each of said primary and secondary substreams to converted digital words that represent respective amplitudes of said predetermined waveform;
• and
• interleaving said primary and secondary substreams to thereby form said periodic stream of digital words that occur at said clock frequency fclk;
• wherein said offsetting step includes the steps of:
• providing n−1 phase steps kφs wherein k represents integers from 1 to n−1;
• and
• subtracting said phase steps kφs from said primary substream to generate said secondary substreams.

A method of generating a periodic stream of digital words that occur at a clock frequency fclk and represent respective amplitudes of a predetermined periodic waveform wherein said periodic stream has a period P and said digital words are spaced by a phase φs that is portion of said period, the method comprising the steps of:

• with a count capacity C, counting modulo nφs at a reduced clock frequency (1/n)fclk to thereby generate a primary substream of digital words;
• phase offsetting said primary substream to form n−1 secondary substreams of digital words wherein said primary and secondary substreams are phase spaced by said phase step φs;
• converting the digital words of each of said primary and secondary substreams to converted digital words that represent respective amplitudes of said predetermined waveform;
• and
• interleaving said primary and secondary substreams to thereby form said periodic stream of digital words that occur at said clock frequency fclk;
• wherein said offsetting step includes the steps of:
• providing n−1 phase steps kφs wherein k represents integers from 1 to n−1;
• and
• adding said phase steps kφs to said primary substream to generate said secondary substreams.

A method of generating a periodic stream of digital words that occur at a clock frequency fclk and represent respective amplitudes of a predetermined periodic waveform wherein said periodic stream has a period P and said digital words are spaced by a phase step φs that is a portion of said period, the method comprising the steps of:

• with a count capacity C, counting modulo nφs at a reduced clock frequency (1/n)fclk to thereby generate a primary substream of digital words;
• phase offsetting said primary substream to form n−1 secondary substreams of digital words wherein said primary and secondary substreams are phase spaced by said phase step φs;
• converting the digital words of each of said primary and secondary substreams to converted digital words that represent respective amplitudes of said predetermined waveform;
• and
• interleaving said primary and secondary substreams to thereby form said periodic stream of digital words that occur at said clock frequency fclk;
• wherein said interleaving step includes the step of multiplexing said primary and secondary streams at said clock frequency fclk.

A method of generating a periodic waveform that has a period P and is quantized in a phase step φs that occurs at a clock frequency fclk, the method comprising the steps of:

• with a count of capacity C, counting modulo nφs at a reduced clock frequency (1/n)fclk to thereby generate a primary substream of digital words;
• phase offsetting said primary substream to form n−1 secondary substreams of digital words wherein said primary and secondary substreams are phase spaced by said phase step φs;
• converting the digital words of each of said primary and secondary substreams to converted digital words that represent respective amplitudes of said periodic waveform;
• interleaving said primary and secondary substreams to thereby form a periodic stream of converted digital words that occur at said clock frequency fclk;
• and
• converting said converted digital words to analog signals, that have said respective amplitudes to thereby form said periodic waveform.

A method of generating a periodic waveform that has a period P and is quantized in a phase step φs that occurs at a clock frequency fclk the method comprising the steps of:

• with a count of capacity C, counting modulo nφs at a reduced clock frequency (1/n)fclk to thereby generate a primary substream of digital words;
• phase offsetting said primary substream to form n−1 secondary substreams of digital words wherein said primary and secondary substreams are phase spaced by said phase step φs;
• converting the digital words of each of said primary and secondary substreams to converted digital words that represent respective amplitudes of said periodic waveform;
• interleaving said primary and secondary substreams to thereby form a periodic stream of converted digital words that occur at said clock frequency fclk;
• and
• converting said converted digital words to analog signals that have said respective amplitudes to thereby form said periodic waveform;
• wherein said offsetting step includes the steps of:
• providing n−1 phase steps kφs wherein k represents integers from 1 to n−1;
• and
• subtracting said phase steps kφs from said primary substream to generate said secondary substreams.

A method of generating a periodic waveform that has a period P and is quantized in a phase step φs that occurs at a clock frequency fclk, the method comprising the steps of:

• with a count of capacity C, counting modulo nφs at a reduced clock frequency (1/n)fclk to thereby generate a primary substream of digital words;
• phase offsetting said primary substream to form n−1 secondary substreams of digital words wherein said primary and secondary substreams are phase spaced by said phase step φs;
• converting the digital words of each of said primary and secondary substreams to converted digital words that represent respective amplitudes of said periodic waveform;
• interleaving said primary and secondary substreams to thereby form a periodic stream of converted digital words that occur at said clock frequency fclk;
• and
• converting said converted digital words to analog signals that have said respective amplitudes to thereby form said periodic waveform;
• wherein said offsetting step includes the steps of:
• providing n−1 phase steps kφs wherein k represents integers from 1 to n−1;
• and
• adding said phase steps kφs to said primary substream to generate said secondary substreams.

A method of generating a periodic waveform that has a period P and is quantized in a phase step φs that occurs at a clock frequency fclk, the method comprising the steps of:

• with a count of capacity C, counting modulo nφs at a reduced clock frequency (1/n)fclk to thereby generate a primary substream of digital words;
• phase offsetting said primary substream to form n−1 secondary substreams of digital words wherein said primary and secondary substreams are phase spaced by said phase step φs;
• converting the digital words of each of said primary and secondary substreams to converted digital words that represent respective amplitudes of said periodic waveform;
• interleaving said primary and secondary substreams to thereby form a periodic stream of converted digital words that occur at said clock frequency fclk;
• and
• converting said converted digital words to analog signals that have said respective amplitudes to thereby form said periodic waveform;
• wherein said periodic waveform is a sinusoidal waveform.

A generator that generates a periodic stream of digital words that occur at a clock frequency fclk and represent respective amplitudes of a predetermined periodic waveform wherein said periodic stream has a period P and said digital words are spaced by a phase step φs that is a portion of said period, the generator comprising:

• a phase accumulator that generates, at a reduced clock frequency (1/n)fclk, a primary substream of digital words wherein said primary substream has said period P and said digital words are spaced by a phase step nφs;
• an offset generator that offsets said primary substream to thereby generate n−1 secondary substreams of digital words wherein said primary and secondary substreams are phase spaced by said phase step φs;
• n phase-to-amplitude converters that each convert a respective one of said primary and secondary substreams to converted digital words that represent respective amplitudes of said periodic waveform;
• and
• a multiplexer that interleaves said primary and secondary substreams to thereby form said periodic stream of digital words that occur at said clock frequency fclk.

A generator that generates a periodic stream of digital words that occur at a clock frequency fclk and represent respective amplitudes of a predetermined periodic waveform wherein said periodic stream has a period P and said digital words are spaced by a phase step φs that is a portion of said period, the generator comprising:

• a phase accumulator that generates, at a reduced clock frequency (1/n)fclk, a primary substream of digital words wherein said primary substream has said period P and said digital words are spaced by a phase step nφs;
• an offset generator that offsets said primary substream to thereby generate n−1 secondary substreams of digital words wherein said primary and secondary substreams are phase spaced by said phase step φs;
• n phase-to-amplitude converters that each convert a respective one of said primary and secondary substreams to converted digital words that represent respective amplitudes of said periodic waveform;
• and
• a multiplexer that interleaves said primary and secondary substreams to thereby form said periodic stream of digital words that occur at said clock frequency fclk;
• wherein said offset generator includes:
• a phase-step generator that provides n−1 phase steps kφs wherein k represents integers from 1 to n−1;
• and
• n−1 differencers that generate said n−1 secondary substreams in response to said primary substream and said n−1 phase step kφs.

A generator that generates a periodic stream of digital words that occur at a clock frequency fclk and represent respective amplitudes of a predetermined periodic waveform wherein said periodic stream has a period P and said digital words are spaced by a phase step φs that is a portion of said period, the generator comprising:

• a phase accumulator that generates, at a reduced clock frequency (1/n)fclk, a primary substream of digital words wherein said primary substream has said period P and said digital words are spaced by a phase step nφs;
• an offset generator that offsets said primary substream to thereby generate n−1 secondary substreams of digital words wherein said primary and secondary substreams are phase spaced by said phase step φs;
• n phase-to-amplitude converters that each convert a respective one of said primary and secondary substreams to converted digital words that represent respective amplitudes of said periodic waveform;
• and
• a multiplexer that interleaves said primary and secondary substreams to thereby form said periodic stream of digital words that occur at said clock frequency fclk;
• wherein said offset generator includes:
• a phase-step generator that provides n−1 phase steps kφs wherein k represents integers from 1 to n−1;
• and
• n−1 adders that generate said n−1 secondary substreams in response to said primary substream and said n−1 phase steps kφs.

A synthesizer that generates a periodic waveform that has a period P and is quantized with a phase step φs at a clock frequency fclk, the synthesizer comprising:

• a phase accumulator that generates, at a reduced clock frequency (1/n)fclk, a primary substream of digital words wherein said primary substream has said period P and said digital words are spaced by a phase step nφs;
• an offset generator that offsets said primary substream to thereby generate n−1 secondary substreams of digital words wherein said primary and secondary substreams are phase spaced by said phase step φs;
• n phase-to-amplitude converters that each convert a respective one of said primary and secondary substreams to converted digital words that represent respective amplitudes of said periodic waveform;
• a multiplexer that interleaves said primary and secondary substreams to thereby form a periodic stream of digital words that occur at said clock frequency fclk;
• and
• a digital-to-analog converter that generates said periodic waveform in response to said periodic stream of digital words.