Wideband error correction elevates time-interleaved ADCs
In Figure 5, measured SFDR performance levels are plotted for the first and second Nyquist frequency band. In the first Nyquist frequency band, the suppression of aliasing distortion due to time-interleaved ADC mismatch occurs in a “correction frequency band” having a low-pass character (see the left-hand part of Figure 5). When the ADC analog input bandwidth is high enough, operation in the second Nyquist frequency band of the ADC array is possible. For Nyquist frequency bands above the first, the correction frequency band has a band-pass character (the right-hand part of Figure 5 shows the post-processing improvement in the second Nyquist frequency band).
From Figure 5 one can conclude measured SFDR performance levels of around 90 and 80 dBFS for the first and second Nyquist frequency band respectively, which is what are typically expected for a single-core 14-bit ADC. The large benefit here is that the sampling frequency has in fact been doubled compared with the state-of-the-art single-core 14-bit ADC. Thus, one can draw the conclusion that digital time-interleaved ADC mismatch error correction makes the SFDR-performance of the time-interleaved ADC array to correspond to that of a single-core ADC. This is true both for solutions using discrete time-interleaved ADCs as well as singe-die ADC implementations.
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