Quaternary/ternary modulation selecting circuit and associated method
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Solution Overview
Problem
Existing class D power amplifiers face challenges in combining the advantages of quaternary and ternary modulation, which offer better total harmonic distortion (THD) and efficiency, respectively, while also managing electromagnetic interference (EMI) performance effectively under varying power conditions.
Innovation Solution
A quaternary/ternary modulation selecting circuit that includes a signal generating circuit, a detecting circuit, and a selecting circuit to dynamically switch between ternary and quaternary modulation based on output power conditions, utilizing comparators, XOR gates, and multiplexers to generate and select signals for the output stage of the amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If quaternary modulation is used, then total harmonic distortion (THD) is improved, but efficiency deteriorates
Solution Approach 1:
The patent implements dynamic switching between quaternary and ternary modulation modes based on real-time signal conditions. The detecting circuit monitors the input signal characteristics and controls the selecting circuit to switch modulation modes, allowing the system to optimize between THD performance and efficiency dynamically rather than being fixed in one mode.
Solution Approach 2:
The patent changes the modulation parameter (number of voltage levels) based on operating conditions. By varying the modulation mode between quaternary (4 levels) and ternary (3 levels) according to signal amplitude and power conditions, the system adapts its parameters to achieve optimal performance across different operating scenarios.
2Use of energy by moving object
If ternary modulation is used, then efficiency is improved, but total harmonic distortion (THD) deteriorates
Solution Approach 1:
The system dynamically selects modulation modes based on real-time detection of signal characteristics. When efficiency is prioritized and signal conditions permit, ternary mode is selected; when THD performance is critical, quaternary mode is selected. This dynamic adaptation resolves the contradiction by making efficiency and THD trade-offs conditional rather than absolute.
Solution Approach 2:
The modulation parameter (voltage level count) is changed based on operating conditions. The detecting circuit identifies when signal amplitude and duration warrant ternary modulation for efficiency, versus when quaternary modulation is needed for lower THD, and switches accordingly.
3Object-generated harmful factors
If ternary modulation is used, then EMI performance is improved, but THD deteriorates
Solution Approach 1:
The patent employs dynamic mode selection to adapt to different operational requirements. The detecting circuit monitors signal characteristics and switches between ternary and quaternary modes, allowing the system to prioritize EMI performance when needed while maintaining THD performance when signal conditions require it.
4Device complexity
If a single modulation mode is used, then device complexity is reduced, but adaptability to different power conditions deteriorates
Solution Approach 1:
The patent segments the modulation function into separate components: a signal generating circuit that produces both ternary and quaternary modulation signals, a detecting circuit that analyzes input signal characteristics, and a selecting circuit that chooses the appropriate mode. This segmentation allows multiple modulation capabilities without requiring a completely separate system for each mode.
Solution Approach 2:
The modulation circuit is designed with multi-functionality to handle both ternary and quaternary modes within a single integrated architecture. The signal generating circuit can produce both types of modulation signals, and the selecting circuit routes the appropriate signal based on detected conditions, making the system universally adaptable to different power and signal conditions.
Data Source
AI summary
A quaternary/ternary modulation selecting circuit of an amplifier includes: a signal generating circuit, a detecting circuit, and a selecting circuit. The signal generating circuit is arranged to generate a ternary signal and a quaternary signal. The detecting circuit coupled to the signal generating circuit is arranged to generate a mode selecting signal according to at least the ternary signal. The selecting circuit coupled to the signal generating circuit and the detecting circuit is arranged to select and output one of the ternary signal and the quaternary signal to an output stage of the amplifier according to the mode selecting signal.