Continuous-Time Delta-Sigma ADC Feedback for Delay-Stable Conversion
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Solution Overview
Problem
Conventional continuous-time delta-sigma analog digital converters face stability issues due to unavoidable delays between quantification and feedback, and are hindered by expensive and power-consuming feedback devices.
Innovation Solution
A feedback system using a switching device coupled capacitively to an integration capacitor, which generates a feedback signal corresponding to the differentiated output signal, reducing delay and power consumption by eliminating the need for summating amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional feedback devices (digital analog converter, summating amplifier) are used, then the converter can provide feedback functionality, but the device complexity and power consumption increase
Solution Approach 1:
The invention extracts and eliminates the complex summating amplifier from the feedback path by directly coupling the switching device output to the integration capacitor. This removes unnecessary components while preserving the essential feedback functionality through capacitive coupling alone.
Solution Approach 2:
The integration capacitor serves multiple functions: it performs integration of the analog signal, stores charge representing the digital output signal, and provides the feedback path through capacitive coupling. This multi-functionality eliminates the need for separate summating amplifier and feedback capacitor components.
2Reliability
If conventional feedback devices (digital analog converter, summating amplifier) are used, then the converter can provide feedback functionality, but the power consumption increases
Solution Approach 1:
The invention removes the power-consuming summating amplifier from the feedback path. The capacitive coupling between the switching device and integration capacitor provides passive feedback without requiring active power consumption, significantly reducing overall converter power usage.
Solution Approach 2:
The switching device operates in periodic cycles, switching between connected and disconnected states from the integration capacitor. This periodic switching action enables feedback functionality while consuming power only during switching transitions, rather than continuous power consumption of conventional amplifiers.
3Reliability
If the feedback signal is transmitted through conventional summating amplifiers, then the feedback can be provided, but additional delay is introduced affecting stability
Solution Approach 1:
By removing the summating amplifier from the feedback path, the invention eliminates the propagation delay introduced by this active component. The direct capacitive coupling provides a faster feedback path with minimal delay, improving converter stability.
Solution Approach 2:
The integration capacitor acts as an intermediary element that directly couples the switching device output to the analog filter input. This capacitive intermediary provides instantaneous charge transfer without the delay characteristics of active amplifier stages, enabling faster feedback response.
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 approach enhances converter stability while reducing power consumption and noise transfer, allowing for high quantification noise suppression within the signal band, and simplifies circuit technology.
Implementation Method 1
a switching device actuated by the digital output signal of the quantifier and coupled capacitively to the integration capacitor
Data Source
AI summary
A continuous-time delta-sigma analog digital converter for converting an analog input signal to a digital output signal, comprising an analog filter with at least one integration capacitor, a cycled quantifier which quantifies the filtered analog signal for generating the digital output signal, and a feedback device with at least one digital analog converter, which supplies at least a first analog feedback signal to the analog filter corresponding to the value of the digital output signal. The feedback device for generating a second feedback signal corresponding to the differentiated output signal of the quantifier, comprises a switching device coupled capacitively to the integration capacitor, by means of which device corresponding charge portions are transmitted to the integration capacitor when there is a variation in the digital output signal.