An 80-MHz, 14-bit bandpass mash sigma-delta/pipeline A/D converter with 5Â MHz bandwidth for third generation mobile communication systems

In this paper a bandpass MASH (multi-stage noise shaping) sigma-delta (ΣΔ) modulator is presented. A SNR (signal to noise ratio) of at least 85 dB (equivalent to a resolution of 14 bits) has been achieved over a 5 MHz band around an intermediate frequency (IF) of 20 MHz using a clock frequency of 80 MHz. This performance is obtained using a sixth order bandpass ΣΔ modulator followed by a 10 bit pipeline converter. The proposed circuit has been extensively simulated, both at behavioral and at circuit level, and results are reported.