RF sampling A/D converters are key components for next generation software defined radio systems. Time-interleaved architecture is leveraged to achieve very high sampling rates and low power consumption at the cost of degraded dynamic range. It has been shown that injecting a constrained calibration signal out of the useful band improves significantly this dynamic range thanks to a low complexity calibration algorithm for gain and timing errors. Measurements on 14/500 Msps prototype showed an approximate 30 dB dynamic range improvement across the two first Nyquist zones. The proposed method can be used for higher-speed applications as long as the gain/timing mismatch error model remains valid.
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The author, Djamel Haddadi holds the post of Technical Leader - RF, High Speed Data Converters at IDT, www.idt.com.