LSR Pulse Width Circuit for Idle-Channel Linearity
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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:
The pulse width control function is segmented into two independent paths: a main LSR signal path and a minimum pulse width enforcement path. The minimum pulse width generator operates independently to ensure adequate pulse widths without interfering with the differential signal integrity, thus reducing non-linearity while avoiding additional differential error
Solution Approach 2:
A dedicated minimum pulse width generator circuit acts as an intermediary component that receives the LSR signal and enforces minimum pulse width requirements through a separate control path. This intermediary structure ensures that pulse width control is achieved without directly modifying the differential signal path, thereby preventing additional differential error and common mode error
2Use of energy by moving object
If LSR pulse widths are made narrow during idle channel to save power, then clock energy is reduced, but non-linearity increases
Solution Approach 1:
The system dynamically adjusts LSR pulse widths based on channel activity status. During active channels, narrow pulse widths are used to minimize power consumption. During idle channels, the minimum pulse width generator dynamically enforces adequate pulse widths to maintain signal linearity, creating a dynamic balance between power efficiency and signal quality
Solution Approach 2:
The pulse width parameter is conditionally changed based on channel state. During idle channels, the minimum pulse width generator ensures pulse widths meet a predetermined threshold, preventing excessive non-linearity. During active channels, the system allows narrower pulse widths to reduce power consumption, achieving parameter optimization based on operational conditions
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.