A 15 b 30 kHz bandpass sigma-delta modulator

The authors introduce a bandpass architecture and implementation that achieves 15-b dynamic range over a 30-kHz bandwidth centered at 1.8 MHz using 7.2-MHz sampling frequency and operating on a single 5-V supply. A z-domain representation of the fourth-order bandpass modulator is shown. It is made up of bandpass filters with infinite Qs as opposed to integrators used in lowpass modulators. A/D (analog-to-digital) converter performance is evaluated by applying a 1.8-MHz sinewave, windowing the one-bit digital output with a Dolph-Chebyshev window, and performing a 65536-point FFT (fast Fourier transform).<
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