A 320-MHz four-paths bandpass sigma-delta modulator

In this paper we present a sigma-delta modulator for wide-band base transceiver station receivers. The modulator, based on a four-path architecture, achieves an equivalent sampling frequency of 320 MHz, although the building blocks operate at only 80 MHz. The circuit achieves 87 dB of signal-to-noise ratio with a signal bandwidth of 5 MHz centered around an intermediate frequency of 80 MHz. Behavioral simulations of the complete sigma-delta modulator, including the most important non-idealities of the building blocks are reported.