SLAAED2A June 2023 – November 2023 TLV320ADC3120 , TLV320ADC3140 , TLV320ADC5120 , TLV320ADC5140 , TLV320ADC6120 , TLV320ADC6140
In this application note, channel summation, a simple but powerful method to increase the dynamic range and SNR of audio ADCs is discussed. This application note demonstrates how the dynamic performance of ADC increase by a factor of 3 dB for every doubling of the number of converters used in parallel.
The channel-summation feature is available in TLV320ADC6140, TLV320ADC5140, TLV320ADC3140, TLV320ADC6120, TLV320ADC5120 and TLV320ADC3120 audio ADCs. Practical results from TLV320ADC6140 are obtained and used to demonstrate this channel summation method in-depth.
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In the audio world, a common technique to increase the dynamic range of a system is to connect two, four or more ADCs in parallel with inputs tied together. This method uses the principle that correlated signals add on linearly whereas uncorrelated signals, such as noise sources, add on as root-sum-square. When using two ADCs, this results in a signal-to-noise ratio (SNR) magnitude increase by 1.414 or 3 dB for two equal amplitudes. In this application note, this technique is discussed in more detail and the equations that yield the improvement are derived.