Digital Front End 4-Phase to 8-Phase Conversion for DDRM Linearity

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current 4-phase Direct-Digital RF Modulators (DDRMs) face limitations in linearity and harmonic distortion, leading to counter-intermodulation products and harmonic distortion, which affect the quality of RF signals.

Innovation Solution

The solution involves converting the 4-phase digital baseband signal to an 8-phase signal at a later stage in the digital frontend, reducing the number of high-power consumption blocks and suppressing unwanted image signals, thereby improving linearity and reducing harmonic distortion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If 4-phase DDRM architecture is used, then device complexity is reduced, but linearity deteriorates and harmonic distortion increases

Engineering Contradiction:

ImproveDDRM architecture complexityVSAvoidsignal linearity

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent segments the single 4-phase DDRM architecture into multiple parallel 4-phase DDRM blocks (first and second DDRM blocks). Each block processes a portion of the signal independently, and their outputs are combined. This segmentation allows for better linearity performance while maintaining manageable device complexity through modular design.

Inventive Principle:

Principle #1Segmentation

2Device complexity

If 4-phase DDRM architecture is used, then device complexity is reduced, but harmonic distortion increases

Engineering Contradiction:

ImproveDDRM architecture complexityVSAvoidharmonic distortion

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces a phase rotation unit that deliberately adds a controlled phase rotation to the baseband signal before processing. This phase rotation is designed to counteract the harmonic distortion generated by the DDRM blocks. By converting the phase information into a corrective mechanism, the system transforms a potential source of distortion into a benefit that improves overall signal quality.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Manufacturing precision

If digital signal processing is enhanced to improve linearity, then signal quality improves, but power consumption increases

Engineering Contradiction:

Improvesignal linearityVSAvoiddigital power consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies phase rotation only to specific signal components rather than processing the entire signal at maximum detail. The phase rotation unit selectively adjusts phase information where needed to improve linearity, rather than applying full digital signal processing to all signal aspects. This partial action approach achieves acceptable linearity improvement while limiting the increase in power consumption.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentEP3516776B1Digital front end for use with direct digital radio frequency modulator

Publication Date: 2022.02.16 HUAWEI TECH CO LTD

Figure 1a
Figure 1b
Figure 1c

AI summary

The disclosure relates to a digital front end (DFE) (100) for a direct digital radio frequency modulator (DDRM), the DFE comprising: an up-sampling unit (101), configured to provide an up-sampled 4-phase digital baseband (DBB) signal (107) comprising in-phase (I) and quadrature (Q) information (105); and a conversion unit (103), configured to convert the up- sampled 4-phase DBB signal (107) to an 8-phase DBB signal (109).