LSR Modulation Circuit With Dual Minimum Pulse Widening
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Solution Overview
Problem
Audio signal chains using low side recycling (LSR) modulation experience high non-linearity during idle channels due to narrow pulse widths, which can be mitigated but at the cost of introducing additional errors.
Innovation Solution
A circuit incorporating a dual minimum pulse generator that widens pulse widths during idle channels to reduce non-linearity without adding differential error, comprising a filter, comparator, converter, and dual minimum pulse generator, which ensures pulses meet a predetermined delay time period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If minimum pulse width generator is used to ensure minimum pulse width of LSR signals, then non-linearity is reduced, but differential error and common mode error are added
Solution Approach 1:
A dual minimum pulse generator is introduced as an intermediary component between the LSR modulation circuit and the output stage. This dual minimum pulse generator receives the LSR signals and generates corrected minimum pulse signals that maintain the required pulse width without introducing differential errors. The dual minimum pulse generator acts as a mediator that transforms the narrow pulses into wider pulses while preserving signal integrity and avoiding the differential error problems associated with traditional minimum pulse width generators.
2Use of energy by moving object
If LSR pulse widths are narrowed during idle channel to save power, then clock energy is reduced, but non-linearity increases
Solution Approach 1:
The system dynamically adjusts the pulse width based on the operating condition. During active channels, the LSR pulses maintain their natural width for optimal power savings. During idle channels, the dual minimum pulse generator dynamically widens the pulses to meet the minimum pulse width requirement, thereby reducing non-linearity. This dynamic adaptation allows the system to optimize between power consumption and signal quality based on real-time channel conditions.
3Duration of action of moving object
If traditional minimum pulse width generator is used, then pulse width is ensured, but additional differential error is introduced
Solution Approach 1:
The dual minimum pulse generator employs an asymmetric architecture where the two pulse generation paths are intentionally designed to be unbalanced in a controlled manner. This asymmetric design ensures that any differential errors introduced in one path are compensated by the other path, resulting in net zero differential error at the output. The asymmetry is strategically designed to maintain pulse width while eliminating differential error, contrary to the symmetric traditional minimum pulse width generator that introduces differential error.
Data Source
AI summary
A circuit includes a filter, a comparator, and converter. A first input of the comparator couples to the output of the filter. A second input of the comparator is configured to receive ramp signal. An input of the converter couples to the output of the comparator. The circuit also includes a dual minimum pulse generator having an input coupled to the output of the converter. The dual minimum pulse generator is configured to, responsive to an input pulse on the input of the dual minimum pulse generator having a pulse width less than a predetermined delay time period, generate a pulse on the first output of the dual minimum pulse generator that has a pulse width equal to a sum of the pulse width of the input pulse and the predetermined delay time period. A driver is coupled to the output of the dual minimum pulse generator.