ADC Noise Shaping Circuit Using Dynamic Amplifier and Small Capacitors
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Solution Overview
Problem
Existing analog-to-digital converters with noise shaping face challenges in reducing power consumption and die space while effectively suppressing noise, as additional noise shaping circuits increase power consumption and require more space.
Innovation Solution
An analog-to-digital converter with an amplifier-based noise shaping circuit using a dynamic amplifier silent on static current, which amplifies residual voltage and provides a switched capacitor network to generate a noise shaping signal, allowing for the use of small capacitors and effective suppression of input-referred noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an additional noise shaping circuit is added to the ADC, then noise suppression performance is improved, but power consumption increases
Solution Approach 1:
The patent combines the noise shaping circuit with the existing SAR ADC structure by integrating the switched capacitor network and dynamic amplifier into the comparison and feedback path. This merging approach allows noise shaping functionality to be added without requiring completely separate additional circuits, thereby improving noise suppression while limiting the increase in power consumption to only the additional active components needed for the noise shaping signal generation.
2Object-affected harmful factors
If an additional noise shaping circuit is added to the ADC, then noise suppression performance is improved, but die space increases
Solution Approach 1:
The noise shaping circuit is nested within the existing ADC architecture by placing the switched capacitor network and dynamic amplifier in the feedback path between the comparator and the capacitor array. This nesting allows the noise shaping functionality to be embedded within the existing structural framework, utilizing available space efficiently rather than adding separate external circuits that would increase overall die area.
3Area of stationary object
If small capacitors are used in the switched capacitor network, then die space is reduced, but input referred noise increases
Solution Approach 1:
The patent introduces a dynamic amplifier as an intermediary element between the switched capacitor network and the rest of the ADC. This dynamic amplifier provides voltage gain that compensates for the reduced capacitance value, thereby maintaining adequate signal level and suppressing input-referred noise even when small capacitors are used. The amplifier acts as a mediator that allows the system to benefit from smaller capacitor sizes without suffering from the associated noise penalty.
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
The solution reduces power consumption and enables a small-sized ADC with effective noise suppression, allowing for reduced capacitor size and improved noise attenuation in analog-to-digital conversion.
Implementation Method 1
The amplifier-based noise shaping circuit uses an amplifier to amplify a residual voltage obtained from the weighted capacitor array
Implementation Method 2
The amplifier-based noise shaping circuit provides a switched capacitor network between the amplifier and the comparator for sampling the amplified residual voltage
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
An analog-to-digital converter (ADC) using an amplifier-based noise shaping circuit. The amplifier-based noise shaping circuit generates a noise shaping signal. A comparator of the ADC has a first input terminal coupled to an output terminal of a capacitive data acquisition converter that captures an analog input, a second input terminal receiving the noise shaping signal, and an output terminal for observation of the digital representation of the analog input. The amplifier-based noise shaping circuit uses an amplifier to amplify a residual voltage obtained from the capacitive data acquisition converter and provides a switched capacitor network between the amplifier and the comparator for sampling the amplified residual voltage and generating the noise shaping signal.