Variable Pulse Stream Modulation for Low-Ripple Zero Crossings
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Solution Overview
Problem
Existing pulse width modulation (PWM) technologies face challenges in reducing ripple near zero crossings and maintaining timing resolution, leading to inefficiencies in digital-to-analog conversion and noise shaping.
Innovation Solution
The implementation of variable stream pulse width modulation (VSPWM) using splitter logic to separate input data into most significant bits (MSBs) and least significant bits (LSBs), where pulse logic generates pulses based on MSBs and edge mover logic adjusts pulse edges based on LSBs, resulting in an enhanced pulse stream with reduced ripple and improved noise shaping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional pulse width modulation is used, then the system is simple to implement, but ripple near zero crossings increases and timing resolution deteriorates
Solution Approach 1:
The input digital data is segmented into two separate fields: a first field containing structure values that determine pulse patterns, and a second field containing pulse placement values that determine edge positions. This segmentation allows independent optimization of pulse generation and edge positioning, resolving the contradiction between implementation simplicity and timing resolution by handling each aspect separately with dedicated logic circuits.
2Device complexity
If traditional pulse width modulation is used, then the system structure is simple, but ripple near zero crossings increases
Solution Approach 1:
By segmenting the data into structure and placement fields, the modulator can apply different processing strategies to each field. The structure field generates the pulse train pattern while the placement field independently adjusts edge positions, enabling ripple reduction through precise edge control without significantly increasing overall structural complexity.
Solution Approach 2:
The pulse placement field enables local adjustment of pulse edges at specific positions within the pulse train. This local quality control allows targeted modification of pulse widths and positions to minimize ripple effects near zero crossings, while maintaining the overall simple modulator structure through field-based processing.
3Ease of operation
If traditional pulse width modulation is used, then noise shaping is less effective, but the system is easier to operate
Solution Approach 1:
The separation of structure and placement fields enables independent optimization of noise shaping characteristics. The placement field can be specifically designed to push quantization noise to higher frequencies while maintaining ease of operation through straightforward field-based processing and combination logic.
Data Source
AI summary
An example device includes splitter logic to split an input sample having a predetermined number of bits into a first segment of most significant bits and a second segment of least significant bits. Pulse logic generates a pattern of pulses that correlate to the values of the most significant bits. Edge mover logic determines edge adjustment data based on the values of the least significant bits, the edge adjustment data representing an adjustment to at least one edge in the pattern of pulses. Combiner logic generates an enhanced pulse stream by adjusting at least one edge in the pattern of pulses based on the edge adjustment data.