Phase coherent numerically controlled oscillator

Patent metadata

Field	Value
Publication number	US-10879845-B2
Application number	US-201916403777-A
Country	US
Kind code	B2
Filing date	May 6, 2019
Priority date	Dec 31, 2018
Publication date	Dec 29, 2020
Grant date	Dec 29, 2020

Abstract

A phase coherent NCO circuit includes a base frequency NCO, a phase seeding circuit, a scaled frequency NCO, a sine/cosine generator. The base frequency NCO is configured to generate base phase values based on a base frequency control word. The phase seeding circuit is coupled to the base frequency NCO. The phase seeding circuit is configured to generate a seed phase value based on the base phase values and a scale factor value. The scaled frequency NCO is coupled to the phase seeding circuit. The scaled frequency NCO is configured to generate oscillator phase values based on the phase seed value and an oscillator frequency control word. The sine/cosine generator is coupled to the scaled frequency NCO. The sine/cosine generator is configured to generate oscillator output samples based on the oscillator phase values.

First claim

What is claimed is:

1. A phase coherent numerically controlled oscillator (NCO) circuit, comprising:
a base frequency NCO comprising:
a base frequency control input; and
a base phase output;

a phase seeding circuit coupled to the base frequency NCO and comprising:
a base phase input coupled to the base phase output; and
a seed phase output;

a scaled frequency NCO coupled to the phase seeding circuit and comprising:
a seed phase input coupled to the seed phase output; and
an oscillator phase output;

a sine/cosine generator comprising:
a phase input coupled to the oscillator phase output; and
a sine sample output;

a phase summation circuit comprising:
a scaled phase input coupled to the oscillator phase output; and
an adjusted oscillator phase output coupled to the phase input of the sine/cosine generator; and

a phase multiplexer comprising a phase offset output coupled to a phase offset input of the phase summation circuit.

2. A phase coherent numerically controlled oscillator (NCO) circuit, comprising:
a base frequency NCO comprising:
a base frequency control input; and
a base phase output;

a phase seeding circuit coupled to the base frequency NCO and comprising:
a base phase input coupled to the base phase output; and
a seed phase output;

a scaled frequency NCO coupled to the phase seeding circuit and comprising:
a seed phase input coupled to the seed phase output; and
an oscillator phase output;

a frequency control selector comprising:
a frequency selection input; and
a frequency control output coupled to a frequency control input of the scaled frequency NCO; and

a change detection circuit comprising;
a frequency selection input coupled to the frequency selection input of the frequency control selector; and
a trigger output coupled to the phase seeding circuit.

3. A phase coherent numerically controlled oscillator (NCO) circuit, comprising:
a base frequency NCO comprising:
a base frequency control input; and
a base phase output;

a phase seeding circuit coupled to the base frequency NCO, and comprising:
a base phase input coupled to the base phase output; and
a seed phase output;

a scaled frequency NCO coupled to the phase seeding circuit, and comprising:
a seed phase input coupled to the seed phase output; and an oscillator phase output;

wherein the phase seeding circuit further comprises a phase multiplier comprising:
a base phase input coupled to the base phase output; and
a scaled phase output;

wherein the phase seeding circuit further comprises a frequency scaler selection circuit comprising a scale value output coupled to a scale value input of the phase multiplier.

4. A phase coherent numerically controlled oscillator (NCO) circuit, comprising:
a base frequency NCO comprising:
a base frequency control input; and
a base phase output;

a phase seeding circuit coupled to the base frequency NCO, and comprising:
a base phase input coupled to the base phase output; and
a seed phase output;

a scaled frequency NCO coupled to the phase seeding circuit, and comprising:
a seed phase input coupled to the seed phase output; and an oscillator phase output;

wherein the phase seeding circuit further comprises a phase multiplier comprising:
a base phase input coupled to the base phase output; and a scaled phase output;

further comprising:
a phase summation circuit comprising:
a scaled phase input coupled to the scaled phase output; and
a seed phase output coupled to the seed phase input; and

a phase multiplexer comprising a phase offset output coupled to a phase offset input of the phase summation circuit.

5. A radio frequency (RF) sampling transceiver, comprising:
a digital mixer circuit; and
a phase coherent numerically controlled oscillator (NCO) circuit coupled to the digital mixer circuit, and comprising:
a base frequency NCO comprising:
a base frequency control input; and
a base phase output;

a phase seeding circuit coupled to the base frequency NCO and comprising:
a base phase input coupled to the base phase output; and
a seed phase output;

a scaled frequency NCO coupled to the phase seeding circuit and comprising:
a seed phase input coupled to the seed phase output; and
an oscillator phase output;

a sine/cosine generator comprising:
a phase input coupled to the oscillator phase output; and
a sine sample output;

a phase summation circuit comprising:
a scaled phase input coupled to the oscillator phase output; and
an adjusted oscillator phase output coupled to the phase input of the sine/cosine generator; and

a phase multiplexer comprising a phase offset output coupled to a phase offset input of the phase summation circuit.

6. A radio frequency (RF) sampling transceiver, comprising:
a digital mixer circuit; and
a phase coherent numerically controlled oscillator (NCO) circuit coupled to the digital mixer circuit, and comprising:
a base frequency NCO comprising:
a base frequency control input; and
a base phase output;

a phase seeding circuit coupled to the base frequency NCO, and comprising:
a base phase input coupled to the base phase output; and
a seed phase output;

a scaled frequency NCO coupled to the phase seeding circuit, and comprising:
a seed phase input coupled to the seed phase output; and an oscillator phase output;

wherein the phase coherent NCO circuit further comprises:
a frequency control selector comprising:
a frequency selection input; and
a frequency control output coupled to a frequency control input of the scaled frequency NCO; and

a change detection circuit comprising:
a frequency selection input coupled to the frequency selection input of the frequency control selector; and
a trigger output coupled to the phase seeding circuit.

7. A radio frequency (RF) sampling transceiver, comprising:
a digital mixer circuit; and
a phase coherent numerically controlled oscillator (NCO) circuit coupled to the digital mixer circuit, and comprising:
a base frequency NCO comprising:
a base frequency control input; and
a base phase output;

a phase seeding circuit coupled to the base frequency NCO, and comprising:
a base phase input coupled to the base phase output; and
a seed phase output;

a scaled frequency NCO coupled to the phase seeding circuit, and comprising:
a seed phase input coupled to the seed phase output; and an oscillator phase output;

wherein the phase seeding circuit further comprises a phase multiplier comprising:
a base phase input coupled to the base phase output; and a scaled phase output;

wherein the phase seeding circuit further comprises a frequency scaler selection circuit comprising a scale value output coupled to a scale value input of the phase multiplier.

8. The RF sampling transceiver of claim 7 , further comprising:
a phase summation circuit comprising:
a scaled phase input coupled to the scaled phase output; and
a seed phase output coupled to the seed phase input; and

a phase multiplexer comprising a phase offset output coupled to a phase offset input of the phase summation circuit.

9. A phase coherent numerically controlled oscillator (NCO) circuit, comprising:
a base frequency NCO configured to generate base phase values based on a base frequency control word;
a phase seeding circuit coupled to the base frequency NCO and configured to generate a seed phase value based on the base phase values and a scale factor value;
a scaled frequency NCO coupled to the phase seeding circuit and configured to generate oscillator phase values based on the phase seed value and an oscillator frequency control word; and
a sine/cosine generator coupled to the scaled frequency NCO, and configured to gen

Assignees

• Texas Instruments Inc

Inventors

• Aremallapur Nagalinga Swamy Basayya
• Murali Sriram
• Tangudu Jawaharlal

Classifications

• H03L7/0994

  comprising an accumulator · CPC title

• G06F1/022

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

• G06F1/0342

  for generating simultaneously two or more related waveforms, e.g. with different phase angles only · CPC title

• H03B21/02 Primary

  by plural beating, i.e. for frequency synthesis {; Beating in combination with multiplication or division of frequency (digital frequency synthesis using a ROM G06F1/02; digital frequency synthesis in general H03K; indirect frequency synthesis using a PLL H03L7/16)} · CPC title

• H03L7/16

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