PWM Duty Cycle Correction for Asymmetric Driver Delays

Solution Overview

Problem

Driver circuits experience asymmetry in delay between paths, leading to distortion in sine waves due to asymmetrical delay and inability to faithfully reproduce intended duty cycles, which conventional closed-loop feedback methods address inefficiently by increasing circuit size and current consumption.

Innovation Solution

A driver circuit with components for duty cycle correction, including a digital modulator, power stage, sampling component, adjustment signal generator, and PWM adjustment component, measures and adjusts duty cycles to match ideal cycles, reducing or eliminating distortion by independently correcting each path's delay.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional closed-loop feedback methods are used to correct duty cycle errors, then duty cycle accuracy is improved, but circuit size and current consumption increase

Engineering Contradiction:

Improveduty cycle accuracyVSAvoidcircuit size

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The correction approach is segmented into separate independent correction components for each PWM path rather than using a unified feedback system. Each path has its own sampling component and adjustment component that operates independently, avoiding the need for complex feedback circuitry while maintaining correction accuracy

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system performs preliminary sampling of the output PWM signal and calculates the duty cycle correction value before the actual PWM output. By pre-calculating the correction based on sampled values and applying it in advance, the system avoids the need for complex real-time feedback mechanisms, thereby reducing circuit complexity while maintaining accuracy

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If conventional closed-loop feedback methods are used to correct duty cycle errors, then duty cycle accuracy is improved, but current consumption increases

Engineering Contradiction:

Improveduty cycle accuracyVSAvoidcurrent consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The correction approach is segmented into separate independent correction components for each PWM path rather than using a unified feedback system. Each path has its own sampling component and adjustment component that operates independently, avoiding the need for complex feedback circuitry while maintaining correction accuracy

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system performs preliminary sampling of the output PWM signal and calculates the duty cycle correction value before the actual PWM output. By pre-calculating the correction based on sampled values and applying it in advance, the system avoids the need for complex real-time feedback mechanisms, thereby reducing circuit complexity while maintaining accuracy

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If asymmetrical delay is present in driver circuit paths, then circuit simplicity is maintained, but signal distortion increases

Engineering Contradiction:

Improvecircuit simplicityVSAvoidsignal distortion

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The system applies local correction to each PWM path independently by sampling the output signal of each path and calculating specific correction values for that path. This localized approach addresses the asymmetrical delay in each path without requiring complex global synchronization mechanisms, thereby maintaining circuit simplicity while eliminating signal distortion

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system uses a simplified feedback mechanism where the output PWM signal is sampled and the duty cycle correction value is calculated based on the sampled value. This correction value is then applied to adjust the PWM signal. The feedback is local to each path and does not require complex inter-path coordination, maintaining simplicity while correcting distortion

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS12494776B2Duty cycle correction

Publication Date: 2025.12.09 QUALCOMM INC

AI summary

In some aspects, a device may comprise a digital modulator to generate a first pulse width modulation (PWM) signal. The device may comprise a first power stage component to generate a first output PWM signal based on the first PWM signal. The device may comprise a first sampling component to sample the first output PWM signal and generate a first sampled output PWM signal. The device may comprise a first adjustment signal generator to generate a first duty cycle adjustment signal based on the first PWM signal and the first sampled output PWM signal. The device may comprise a first PWM adjustment component to adjust a duty cycle of the first PWM signal based on the first duty cycle adjustment signal in association with correcting a duty cycle of the first output PWM signal to generate a corrected first PWM signal. Numerous other aspects are described.