ADC Decimation Filter for Transducer Frequency Response Flattening

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Solution Overview

Problem

Conventional systems for correcting frequency characteristics of transducers, such as microphones, often require complex configurations with separate analog filters, leading to system complications and potential signal distortion due to resonant frequencies within or near the signal band.

Innovation Solution

An analog-to-digital converter (ADC) with a sigma delta modulator for oversampling and a filter for decimation and frequency characteristics correction, using a filter control signal to ensure flat frequency response across the signal band, eliminating the need for a separate analog filter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a separate analog filter is used to correct frequency characteristics, then frequency response flatness is improved, but system complexity increases

Engineering Contradiction:

Improvefrequency response flatnessVSAvoidsystem configuration

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent combines the frequency characteristics correction function with the decimation filter in the digital domain. The decimation filter is configured with specific coefficients to simultaneously perform decimation and compensate for transducer resonance, eliminating the need for a separate analog filter and reducing system complexity while maintaining frequency response flatness

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces the mechanical/analog filter system with a digital signal processing approach. By using digital filtering and coefficient optimization in the digital domain, the system achieves frequency correction without requiring physical analog filter components, thereby simplifying the overall system configuration

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If an analog filter is added for frequency correction, then frequency characteristics are improved, but device size increases

Engineering Contradiction:

Improvefrequency characteristicsVSAvoiddevice size

Core Design Contradiction:

Manufacturing precisionVSArea of stationary object

Solution Approach 1:

The patent merges the frequency correction function into the existing decimation filter structure. The same filter that performs decimation also applies frequency characteristics correction through optimized coefficients, eliminating the need for additional analog filter components and reducing overall device size

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent substitutes physical analog filter components with digital signal processing algorithms. This replacement eliminates the need for additional hardware components that would increase device size, while achieving the same frequency correction objective through software-based filtering

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If a separate analog filter is used, then frequency response is improved, but power consumption increases

Engineering Contradiction:

Improvefrequency responseVSAvoidpower consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by stationary object

Solution Approach 1:

The patent combines frequency correction with the decimation operation in a single digital processing stage. By performing both functions simultaneously through optimized filter coefficients, the system avoids the additional power consumption that would result from operating a separate analog filter circuit

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces power-hungry analog filter circuits with digital signal processing operations. Digital filtering consumes significantly less power than analog filter components, especially when integrated into existing processing stages like decimation, thereby reducing overall system power consumption

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS10848173B2Analog-to-digital converter correcting frequency characteristics and semiconductor device including the same

Publication Date: 2020.11.24 SEOUL NATIONAL UNIVERSITY R&DB FOUNDATION

AI summary

An analog-to-digital converter (ADC) includes a modulator configured to oversample an input signal generated from an output signal of a transducer; and a filter configured to perform a decimation operation on an output from the modulator and a frequency characteristics correction operation according to a filter control signal on the output from the modulator, wherein the frequency characteristics correction operation is performed to complement a frequency characteristics of the output signal of the transducer such that overall frequency characteristics of the transducer and the filter be flat in a signal band.