Dual-Supply Amplifier Without an Inter-Stage Capacitor
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing dual supply amplifiers in integrated circuits require an inter-stage capacitor, which occupies a large area and is costly, due to the need for both low-V and high-V amplification stages to handle signals larger than the supply voltage, especially in miniaturized applications like headphones.
Innovation Solution
A dual supply amplifier design that integrates low-V and high-V stages without an inter-stage capacitor by using an input stage to generate a voltage signal proportional to the input difference, a conversion stage to generate signals referenced to different supply voltages, and an output stage to produce a signal with a swing near the higher supply voltage and ground, potentially using a negative potential for the third supply voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an inter-stage capacitor is used to isolate the low-V amplification stage and the high-V amplification stage, then the amplifier can handle signals larger than the supply voltage, but the capacitor occupies a large area in the integrated circuit
Solution Approach 1:
The patent extracts and eliminates the inter-stage capacitor from the amplifier circuit by redesigning the signal path. The conversion stage directly couples the low-V stage output to the high-V stage input through careful voltage reference management, removing the need for capacitor-based isolation while maintaining the ability to handle large signals across different supply voltages.
Solution Approach 2:
The patent changes the voltage reference parameters between stages. The conversion stage generates signals V1 and V2 with references to VDD2 and VDD3 respectively, allowing direct coupling without capacitor isolation. This parameter transformation enables the system to handle signals larger than the low-V supply while eliminating the area-consuming capacitor.
2Adaptability or versatility
If an inter-stage capacitor is used to isolate the amplification stages, then the amplifier can handle large signals, but the circuit structure becomes costly and inefficient
Solution Approach 1:
The patent removes the inter-stage capacitor and associated isolation circuitry, simplifying the overall device structure. The conversion stage directly interfaces the low-V and high-V amplification stages through voltage reference transformation, reducing component count and structural complexity while maintaining large signal handling capability.
Solution Approach 2:
The patent merges the functions of voltage level shifting and signal amplification into a unified conversion stage. By generating signals V1 and V2 with appropriate voltage references simultaneously, the circuit combines multiple functions in one stage, reducing overall device complexity compared to separate capacitor-based isolation and voltage shifting circuits.
3Adaptability or versatility
If a low-V amplification stage and a high-V amplification stage are used together, then the amplifier can handle real-world signals such as voice signals, but an inter-stage capacitor is required to isolate the stages
Solution Approach 1:
The patent transforms the voltage reference parameters in the conversion stage to enable direct coupling between low-V and high-V stages. By generating signal V1 referenced to VDD2 and signal V2 referenced to VDD3, the circuit adapts the voltage levels appropriately without requiring capacitor isolation, thus maintaining real-world signal processing capability while eliminating the area-consuming capacitor.
Solution Approach 2:
The conversion stage acts as an intermediary between the low-V and high-V amplification stages. It receives the voltage signal V3 from the low-V stage and transforms it into signals V1 and V2 with appropriate voltage references for the high-V stage, mediating the interface without requiring capacitor-based isolation and enabling direct coupling.
Data Source
AI summary
A dual supply amplifier without using an inter-stage capacitor is disclosed. The dual supply amplifier has an input stage coupled to a lower supply voltage VDD1 for generating a voltage signal V3 proportion to a difference between a pair of inputs. A conversion stage is coupled a higher supply voltage VDD2 and a third supply voltage VDD3, which can be ground or a negative potential, for generating a signal V1 with reference to VDD2 and a signal V2 with reference to VDD3. An output stage receives V1 and V2 for generating an output signal Vo with a swing between VDD2 and VDD3.