Headphone Driver Power Supply Circuit for Stable Negative Rail
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Solution Overview
Problem
Existing headphone driving circuits face instability in negative power supply conversion and require complex circuit constellations due to the need for differential signal paths to isolate noise from the input signal, complicating the provision of stable positive and negative power supplies to operational amplifiers.
Innovation Solution
A power supply circuit comprising a reference voltage generator, voltage regulator, switch driver, level shifter, and power switch unit, which generates and stabilizes constant voltages +Vreg and -Vreg using an operational amplifier, resistors, and transistors to drive capacitors and provide balanced power to the amplifier, eliminating the need for a balanced signal path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a positive power supply is converted to negative power supply to drive the operational amplifier, then the operational amplifier can be driven, but the negative power supply becomes unstable and the circuit constitution becomes very complicated
Solution Approach 1:
The power supply circuit is segmented into separate positive and negative power supply generation paths. The positive power supply +Vreg is generated independently through the voltage regulator circuit, while the negative power supply -Vreg is generated separately through the power switch unit and capacitor configuration, eliminating the instability inherent in conversion-based approaches.
Solution Approach 2:
A capacitor is introduced as an intermediary energy storage element between the power switch unit and the operational amplifier. This capacitor stabilizes the negative power supply voltage by filtering out fluctuations and providing a clean, stable -Vreg potential to the operational amplifier, resolving the stability issue.
2Object-affected harmful factors
If a differential signal path is used to isolate noise from the input signal, then noise isolation is achieved, but the circuit constitution becomes very complicated
Solution Approach 1:
The noise isolation function is extracted from the signal path and integrated into the power supply circuit itself. By providing clean, regulated positive and negative power supplies through separate generation paths with proper filtering, the power supply circuit inherently isolates noise without requiring additional differential signaling components in the signal path.
Solution Approach 2:
The noise isolation function is merged with the power supply regulation function. The voltage regulator and power switch unit not only generate stable voltages but also inherently filter noise through their regulation mechanisms and capacitor filtering, combining two functions into one integrated circuit block.
3Reliability
If stable positive and negative power supplies are provided to the amplifier, then the amplifier can operate reliably, but the circuit constitution becomes complicated
Solution Approach 1:
The power supply circuit is designed as a universal module that simultaneously provides both positive and negative regulated voltages to the operational amplifier through a single integrated circuit block. This multi-functional design achieves reliable amplifier operation without requiring separate independent power supply circuits for each voltage rail.
Data Source
AI summary
A power supply circuit including a voltage regulator and a headphone driving circuit employing the same are disclosed. In accordance with the present invention, the power supply circuit may provide stable power supply to the amplifier since the power supply circuit generates the constant voltage +Vreg and the constant voltage −Vreg from +VDD robust to stronger than a power noise, and the balanced signal path for isolating the noise of the input signal to be amplified is not required, thereby simplifying the constitution of the circuit.