Class D Amplifier PWM Circuit With Integrated Triangular Wave Generation
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Solution Overview
Problem
Class D amplifiers require complex triangular wave generation circuits, which occupy significant chip area and increase production costs when integrated into a single chip.
Innovation Solution
Incorporating a PWM circuit, buffer amplifying circuit, low-pass filter, first and second current sources, and a control circuit that periodically charges and discharges a feedback node to generate a triangular wave signal, eliminating the need for a separate triangular wave generation circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate triangular wave generation circuit is used, then the PWM signal can be generated accurately, but the chip area increases and production cost increases
Solution Approach 1:
The patent merges the triangular wave generation function with the existing integrator circuit in the PWM module. The integrator's feedback node serves dual purposes: maintaining its original integration function while also generating the triangular wave signal through controlled current charging and discharging. This eliminates the need for a separate triangular wave generation circuit, reducing chip area while maintaining PWM signal accuracy.
Solution Approach 2:
The integrator circuit is given multi-functionality by making its feedback node serve both its original purpose and as the generation point for the triangular wave signal. The feedback node participates in both the integration process and the triangular wave generation through the control circuit's selective connection to current sources, allowing one component to perform multiple functions.
2Adaptability or versatility
If a complex triangular wave generation circuit is integrated into the class D amplifier, then the amplifier functionality is complete, but the production cost increases
Solution Approach 1:
The patent combines the triangular wave generation circuitry with the PWM module's existing integrator, sharing common components such as the feedback node and current sources. This merging reduces the total component count and simplifies the manufacturing process while ensuring the class D amplifier maintains complete functionality for PWM signal generation.
Solution Approach 2:
The integrator circuit serves itself by having its feedback node perform dual functions. The same node that maintains integration functionality also generates the triangular wave signal when activated by the control circuit, eliminating the need for separate dedicated triangular wave generation components and reducing production complexity.
3Area of stationary object
If the triangular wave generation is integrated within the PWM circuit, then the chip area is reduced, but the circuit complexity increases
Solution Approach 1:
The circuit uses dynamic control through the control circuit that selectively connects current sources to the integrator's feedback node based on operational requirements. This dynamic switching allows the same hardware to serve multiple functions (integration and triangular wave generation) without requiring permanently dedicated components for each function, thereby reducing chip area while managing complexity through time-multiplexed operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces chip area and hardware costs by integrating the triangular wave generation within the class D amplifier, ensuring accurate signal conversion without the complexity of external triangular wave circuits.
Implementation Method 1
Both the first current source and the second source are electrically connected to a feedback node in the PWM circuit. The first current source is applied for providing a first current flowing into the feedback node, and the second current source is applied for providing a second current flowing out from the feedback node.
Data Source
AI summary
A class D amplifier including a PWM circuit, a buffer amplifying circuit, a low-pass filter, and two current sources is provided. The PWM circuit transfers an analog signal into a PWM signal. The buffer amplifying circuit amplifies the PWM signal and generates an amplified signal. The low-pass filter will filter high frequency components out from the amplified signal and then transmit the filtered signal to a loading of the class D amplifier. The two current sources provide currents flowing into and out from a feedback node in the PWM circuit, respectively. The charging and discharging provided by the two current sources can generate a triangular signal for the PWM circuit.