Capacitive Divider Class D Amplifier for Compact IC Integration
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Solution Overview
Problem
Class D power amplifiers face challenges in simplifying their implementation for integration into a small area on an integrated circuit, particularly due to the complexity of inductor-based output stages and the need for multiple transistors, which occupies significant space.
Innovation Solution
A bridge amplifier design utilizing a switchable capacitive divider that eliminates the need for inductors by combining capacitive voltage division with switching power circuits, allowing for a more compact integration and reduced transistor count, and incorporating a voltage multiplier for power boost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If inductors are used in the output stage to achieve accurate superposition of parallel half-bridge stage outputs, then the multi-level PWM output signal accuracy is improved, but the occupied area increases significantly
Solution Approach 1:
The patent removes inductors from the output stage entirely, extracting the harmful element that causes large occupied area. Instead of using inductors for superposition, the invention uses a different architecture (single half-bridge stage with capacitive voltage divider) that achieves multi-level output without requiring inductive components, thus resolving the contradiction between accuracy and area.
Solution Approach 2:
The patent replaces the inductor-based superposition mechanism with a capacitor-based voltage division system. By using capacitive voltage dividers in combination with a single half-bridge switching stage, the system achieves the same multi-level output function without mechanical/inductive components, reducing occupied area while maintaining signal accuracy.
2Power
If multiple transistors are used in parallel half-bridge stages to generate multi-level PWM output, then the output power capability is improved, but the device complexity increases
Solution Approach 1:
The patent makes a single half-bridge stage perform multiple functions by combining it with a capacitive voltage divider system. The same switching stage generates multiple output levels (0, Vs/2, Vs) through capacitive division rather than requiring multiple parallel stages, thus reducing transistor count and circuit complexity while maintaining power capability.
Solution Approach 2:
The patent merges the voltage generation function and the switching function into a single integrated architecture. Instead of having separate parallel half-bridge stages for different voltage levels, the invention combines one half-bridge stage with a capacitive voltage divider to generate all required voltage levels, simplifying the overall circuit structure.
3Stability of the object's composition
If a capacitive divider with continuous capacitor interchanging is used to generate half supply voltage, then the voltage stability is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent pre-charges the capacitors to specific voltage levels (0, Vs/2, Vs) before switching operations. By preparing the capacitors in advance with the correct voltages, the system achieves stable output voltages without requiring complex continuous interchanging mechanisms, simplifying the manufacturing while maintaining voltage stability.
Solution Approach 2:
The patent uses dynamic switching of pre-charged capacitors to generate stable voltage levels. The capacitors are switched between different connection states (series, parallel, disconnected) based on the required output level, providing stable voltages through controlled dynamic operation rather than continuous mechanical interchanging.
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 design enables a more compact and efficient power amplifier implementation, reducing occupied area and increasing output power while minimizing conductive losses and dynamic switching losses, suitable for integration on a single chip with improved power delivery to loads like loudspeakers.
Implementation Method 1
a switcheable capacitive divider (10, C2) for dividing a supply voltage delivered to the amplifier (1)
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention refers to an amplifier (1) comprising a switcheable capacitive divider (10) for dividing a supply voltage delivered to the amplifier (1), the switcheable capacitive divider being coupled to a coupling circuit (15) via a first wire and a second wire, the coupling circuit determining a connection path between said first and second wire and a first capacitor (C2) and a switcheable power circuit (20).