Bit Polarization Coding for Low-Noise A/D and D/A Conversion

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Solution Overview

Problem

Conventional A/D and D/A converters induce significant digital noise due to simultaneous changes in multiple binary bits when an analog signal crosses zero voltage, particularly in applications with signals centered at 0V and frequent deviations, which existing solutions like Gray Coding address but at the cost of complex circuitry.

Innovation Solution

The implementation of bit polarization format coding, where a portion of the bits in the digital code are inverted to balance changes from 0s to 1s and vice versa, reducing the number of simultaneous bit changes and thereby minimizing digital noise, using a BPF coder and decoder to modify and recover digital codes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-generated harmful factors

If conventional digital coding is used in A/D converters, then the circuit implementation is simple, but significant digital noise is induced when multiple binary bits change simultaneously

Engineering Contradiction:
Improvedigital noiseVSAvoidcircuit complexity
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The patent changes the parameter of bit inversion by applying a predetermined inversion pattern to specific bit positions. This transforms the digital code bits according to a fixed pattern, ensuring that when analog signals cross zero voltage, only approximately half of the bits change state simultaneously, thereby reducing digital noise while keeping the circuit implementation straightforward

Inventive Principle:
Principle #35Parameter changes

2Object-generated harmful factors

If Gray Coding is used to reduce digital noise, then digital noise is minimized, but the circuitry becomes complex

Engineering Contradiction:
Improvedigital noiseVSAvoidcircuit complexity
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

Instead of using Gray Coding's complex sequential bit change mechanism, the patent applies a simpler parameter change approach by inverting specific bit positions according to a predetermined pattern. This achieves similar noise reduction效果 with significantly simpler circuitry, as it only requires simple inversion logic rather than complex Gray code conversion circuits

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs a lightweight and simple inversion pattern application mechanism rather than complex Gray coding circuits. The inversion pattern can be implemented with minimal logic elements, making it a cost-effective and simple solution compared to the expensive and complex Gray coding implementation

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Data Source

PatentEP2107745B1Method and system for bit polarization coding
Publication Date: 2014.12.31 LINEAR TECHNOLOGY CORP
  • EP2107745B1 patent drawingFigure 1(a)
  • EP2107745B1 patent drawingFigure 1(b)
  • EP2107745B1 patent drawingFigure 1(c)

AI summary

A method and system for converting a digital code. A digital signal is encoded to have a digital code having multiple binary bits. Substantially one half of the binary bits of the digital code is inverted to produce a modified digital code to reduce digital noise associated with the digital code.