Variable Quantizer Scaling for Noise Shaping Dynamic Range

Solution Overview

Problem

Existing signal processing circuits face challenges in reducing quantization noise and increasing dynamic range without causing transient audible phenomena, such as 'pop', due to fixed scaling factors that lead to suboptimal performance at varying input signal levels.

Innovation Solution

A signal processing circuit with a dynamic range optimization circuit that adjusts scaling factors on the fly based on the absolute value of the noise shaping input signal, maintaining a constant ratio between scaling factors to minimize quantization noise and prevent audible transients.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a fixed scaling factor is used in the quantizer, then the device complexity is reduced and ease of operation is improved, but the dynamic range is limited and quantization noise increases at varying input signal levels

Engineering Contradiction:

Improveease of operationVSAvoiddynamic range

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent implements a dynamic scaling factor that varies based on the input signal level. The scaling factor is adjusted according to the absolute value of the noise shaping input signal, allowing the quantizer to adapt to different signal conditions. This dynamic adjustment increases dynamic range and reduces quantization noise while maintaining operational simplicity through automated control.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the scaling factor parameter based on the input signal characteristics. When the absolute value of the noise shaping input signal is below a threshold, a first scaling factor is used; when above the threshold, a second scaling factor is used. This parameter change optimizes quantization performance across different signal levels without increasing device complexity.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If a fixed scaling factor is used in the quantizer, then the device complexity is reduced, but the quantization noise increases at varying input signal levels

Engineering Contradiction:

Improvedevice complexityVSAvoidquantization noise

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent implements a dynamic scaling factor that varies based on the input signal level. The scaling factor is adjusted according to the absolute value of the noise shaping input signal, allowing the quantizer to adapt to different signal conditions. This dynamic adjustment increases dynamic range and reduces quantization noise while maintaining operational simplicity through automated control.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the scaling factor parameter based on the input signal characteristics. When the absolute value of the noise shaping input signal is below a threshold, a first scaling factor is used; when above the threshold, a second scaling factor is used. This parameter change optimizes quantization performance across different signal levels without increasing device complexity.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If the scaling factor is adjusted on the fly to increase dynamic range, then the dynamic range is improved, but transient disturbances occur that manifest as audible pops

Engineering Contradiction:

Improvedynamic rangeVSAvoidtransient disturbance

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary action by adjusting the scaling factor based on the current input signal level before quantization occurs. The dynamic range optimization circuit continuously monitors the noise shaping input signal and adjusts the scaling factor proactively, preventing transient disturbances rather than reacting to them after they occur.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by using the noise shaping input signal to control the scaling factor selection. The absolute value of the input signal provides feedback to the dynamic range optimization circuit, which adjusts the scaling factor accordingly. This feedback mechanism ensures smooth transitions and prevents transient disturbances that would manifest as audible pops.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS12003247B2Noise shaper variable quantizer

Publication Date: 2024.06.04 STMICROELECTRONICS SRL

AI summary

A signal processing circuit includes a filter generating a quantizer input signal from a noise shaping input signal and a quantizer output signal. A quantizer divides the quantizer input signal by a scaling factor to produce a noise shaping output signal and multiplies the noise shaping output signal by the scaling factor to produce the quantizer output signal. Receiver circuitry scales the quantizer output signal by a second scaling factor. A dynamic range optimization circuit compares a current value of the noise shaping input signal to a threshold value, lowers or raises the scaling factor in response to the comparison, and proportionally lowers or raises the scaling factor such that a ratio between the scaling factor and second scaling factor remains substantially constant.