Hybrid Multi-Level Converter Amplifier Nonlinear Sampling Compensation

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Solution Overview

Problem

Multi-level converter amplifiers suffer from non-linearities due to early sampling of analog integrators, leading to performance degradation and stability issues.

Innovation Solution

Implement an analog loop filter with a non-linear function applied to the signal path to compensate for non-linearities introduced by early sampling, using a combination of analog and digital loop filters to achieve higher-order noise shaping and correct for errors caused by early sampling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If early sampling of analog integrators is used in multi-level converter amplifiers, then device complexity is reduced and switching speed is improved, but non-linearity is introduced leading to performance degradation

Engineering Contradiction:

Improvecomplexity of loop filter systemVSAvoidlinearity of amplifier response

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

A digital compensation filter is introduced as an intermediary component between the early sampler and the digital pulse-width modulation controller. This filter receives the sampled values from the analog integrators and applies digital filtering and compensation to correct the non-linearities introduced by early sampling, thereby maintaining manufacturing precision while allowing early sampling to be used

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system changes the timing parameter of sampling from end-of-frame to early sampling (during the frame period). By adjusting this temporal parameter and compensating through digital filtering, the system achieves both reduced device complexity and maintained linearity through the compensation algorithm that accounts for the early sampling timing

Inventive Principle:

Principle #35Parameter changes

2Speed

If early sampling is implemented, then switching speed and response time are improved, but non-linearity and stability issues arise

Engineering Contradiction:

Improveswitching speed of amplifierVSAvoidstability of amplifier system

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The digital compensation filter implements a feedback mechanism where the sampled values from analog integrators are processed through digital filtering algorithms that compensate for the non-linearities. This feedback loop corrects the distortion introduced by early sampling, maintaining system stability while preserving the fast switching speed benefits

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The compensation filter is designed to pre-correct for the known non-linearities introduced by early sampling. By calculating and applying compensation factors in advance based on the sampling timing and integrator characteristics, the system maintains stability before the non-linearities can cause problems

Inventive Principle:

Principle #10Preliminary action

3Use of energy by moving object

If analog loop filter with early sampling is used, then power efficiency is improved, but in-band distortion increases

Engineering Contradiction:

Improvepower efficiency of amplifierVSAvoiddistortion in audio output

Core Design Contradiction:

Use of energy by moving objectVSManufacturing precision

Solution Approach 1:

The system replaces complex analog filtering circuitry with digital filtering implemented in the digital pulse-width modulation controller. This substitution maintains power efficiency by avoiding additional analog components while the digital compensation algorithms effectively reduce in-band distortion introduced by early sampling

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS12531526B2Non-linear function in an early-sampled hybrid multi-level converter amplifier system

Publication Date: 2026.01.20 CIRRUS LOGIC INC

AI summary

A system may include an analog loop filter comprising a plurality of analog integrators, the analog loop filter configured to receive an analog signal input and a feedback output signal, at least one sampler for sampling outputs of the analog integrators, a second loop filter coupled between an output of an analog pulse-width modulation driver and a digital pulse-width modulation controller, wherein the second loop filter comprises at least one integrator and is configured to receive sampled outputs of the analog integrators from the at least one sampler and receive a feedback pulse-width modulation signal from the analog pulse-width modulation driver, and a correction subsystem configured to apply a non-linear function to a signal path of the second loop filter in order to compensate for non-linearity introduced as a result of sampling outputs of the analog integrators.