Phase-Coherent NCO Frequency Hopping Without Resynchronization

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Solution Overview

Problem

Conventional radio frequency (RF) systems using numerically controlled oscillators (NCOs) for frequency shifting face increased latency due to resynchronization requirements, and employing multiple NCOs or oscillators increases area, power usage, and cost.

Innovation Solution

Implementing a mixer with multiple phase accumulators and a multiplexer that use a single oscillator, such as a sine generator, to achieve phase coherent frequency hopping, eliminating the need for resynchronization and minimizing area and power usage by continuously generating frequency ramp signals across multiple phase accumulators.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a generic NCO continuously generates a signal based on a single frequency, then frequency shifting can be achieved, but resynchronization is required following a frequency update resulting in increased latency

Engineering Contradiction:

Improvephase coherencyVSAvoidlatency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The NCO is segmented into multiple parallel NCOs, each generating a signal at a different frequency. This allows the system to switch between frequencies without resynchronization, eliminating latency while maintaining phase coherency through the use of phase accumulators in each parallel NCO

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Multiple NCOs are prepared in advance, each with its own phase accumulator continuously generating signals at predetermined frequencies. When a frequency update is needed, the system simply switches to the pre-prepared NCO operating at the desired frequency, eliminating the resynchronization delay that would otherwise occur

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If multiple NCOs or multiple oscillators are used to shift frequency, then frequency hopping capability is improved, but area and power usage increase and cost increases

Engineering Contradiction:

Improvefrequency hopping capabilityVSAvoidarea usage

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

A single NCO structure is designed to perform multiple functions by incorporating multiple phase accumulators that can be selectively activated. Each phase accumulator can generate signals at different frequencies, allowing one NCO to replace what would traditionally require multiple separate NCOs, thereby reducing area and power usage while maintaining frequency hopping capability

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS10917077B1Phase coherent and frequency hopping numerically controlled oscillator

Publication Date: 2021.02.09 XILINX INC

AI summary

A device includes a plurality of phase accumulators, a multiplexer, and an oscillator. The plurality of phase accumulators is configured to receive a plurality of frequencies and generate a plurality of ramp signals. The multiplexer is configured to receive the plurality of ramp signals from the plurality of phase accumulators and to select one ramp signal from the plurality of ramp signals. The oscillator is configured to receive the one selected ramp signal and to generate one amplitude signal associated therewith. The plurality of phase accumulators continues generating their respective ramp signal. The multiplexer subsequent to selecting the one ramp signal is configured to select another ramp signal associated with another one phase accumulator of the plurality of phase accumulators. The oscillator is further configured to receive the selected another ramp signal and to generate another amplitude signal associated therewith.