1-GHz Input bandwidth 6-bit under-sampling A/D converter for UWB-IR receiver

Abstract

A 1-GHz input bandwidth 6-bit analog-to-digital (A/D) converter is described. The A/D converter is designed for an ultra-wideband impulse radio (UWB-IR) receiver that needs to digitize an input signal with a higher frequency than the sampling frequency. With the proposed under-sampling technique, sampling is executed with low-current consumption by separating a sampling capacitor from an operational amplifier and accumulating the offset voltage of the amplifier in another capacitor. In addition, a low-power comparator is proposed, which reduces bias current dynamically corresponding to its input voltage level. The A/D converter is implemented in a 0.18-mum CMOS process technology, which achieves an effective number of bits of 4.9 for input signals with frequencies greater than 1 GHz at 32 M samples/s, and consumes 0.89 mA at a 1.8-V supply. The converter occupies a 0.18 mm2 area.