A 500 MHz CMOS anti-alias filter using feed-forward op-amps with local common-mode feedback

A 500 MHz op-amp-RC filter in a 0.18 /spl mu/m CMOS process achieves an integrator signal swing of 1.73 V/sub pp/ for -40 dB THD and thermal noise of 18 nV//spl radic/Hz. A three-stage op-amp with two feed-forward paths and common-mode feedback local to each stage is used. The op-amp features 8 GHz unity-gain frequency and 40 dB gain at 500 MHz.