Intra-Package EMI Suppression by Aligning DC-DC and ADC Filter Frequencies
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Solution Overview
Problem
In modern devices, direct current to direct current (DC-to-DC) converters can unintentionally interfere with adjacent analog-to-digital converters (ADCs) due to electromagnetic interference (EMI), affecting the performance of the ADC by introducing input DC offset voltage, thermal drift, total harmonic distortion, and signal-to-noise ratio.
Innovation Solution
A device comprising a DC-to-DC converter with a frequency control device that sets discrete converter frequencies to align with the filter frequencies of the ADC, thereby reducing EMI by positioning these frequencies at odd or even notches of the ADC's filter response, ensuring they are attenuated and do not alias to zero frequency or the baseband.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a DC-to-DC converter is placed adjacent to an ADC in a single device package, then device integration and miniaturization are improved, but electromagnetic interference is introduced that degrades ADC performance
Solution Approach 1:
The patent changes the frequency parameter of the DC-to-DC converter to align with the ADC's filter notches. By adjusting the converter frequency to match specific attenuation frequencies of the ADC's anti-aliasing filter, the harmful electromagnetic interference is converted into a beneficial alignment where the interference signals are naturally suppressed by the filter, thus maintaining close proximity without performance degradation
Solution Approach 2:
The patent converts the harmful electromagnetic interference from the DC-to-DC converter into a beneficial situation by aligning the converter frequency with the ADC's filter notches. The interference signals, which would normally degrade performance, are now positioned at frequencies where the ADC's anti-aliasing filter provides maximum attenuation, effectively using the filter's inherent characteristics to suppress the interference
2Productivity
If the DC-to-DC converter operates at high frequency to improve conversion efficiency, then power conversion performance is improved, but electromagnetic interference and signal distortion increase
Solution Approach 1:
The patent optimizes the converter frequency parameter to achieve a balance between conversion efficiency and interference generation. By setting the frequency to align with ADC filter notches rather than simply maximizing switching frequency, the system maintains efficient power conversion while ensuring that any remaining interference components are suppressed by the ADC's filtering characteristics
3Stability of the object's composition
If the DC-to-DC converter frequency is increased to reduce ripple, then output voltage stability is improved, but interference with ADC sampling increases
Solution Approach 1:
The patent converts the potential interference problem into a benefit by aligning converter frequencies with ADC filter notches. The ripple and interference signals generated by the converter are positioned at frequencies where the ADC's anti-aliasing filter provides maximum attenuation, ensuring that voltage stability is achieved without compromising ADC measurement precision
Solution Approach 2:
The patent utilizes the periodic nature of both the converter switching and ADC sampling by aligning their frequency relationships. By setting the converter frequency to match specific relationships with the ADC sampling frequency (aligning with filter notches), the periodic interference patterns are converted into periodic signals that are naturally suppressed by the filter's frequency-selective attenuation
Data Source
AI summary
A device includes a voltage converter and an analog to digital converter (ADC). The voltage converter includes an input to receive a first voltage and an output to output a second voltage based on a switching signal having a first discrete converter frequency and a second discrete converter frequency. The ADC is coupled to and proximate to the voltage converter. The ADC includes a digital filter configured to substantially attenuate a first filter frequency and a second filter frequency. The voltage converter further includes a frequency control device configured to set the first discrete converter frequency and the second discrete converter frequency so that the first discrete converter frequency is approximately equal to the first filter frequency and the second discrete converter frequency is approximately equal to the second filter frequency.