A Receiver Architecture for Dual-Antenna Systems

The signals received by two antennas can be processed by a single time-shared receiver but only in the absence of interferers and channel-select filters. A low-IF receiver architecture is introduced that translates two antenna signals to positive and negative frequencies in the complex domain, reducing the number of baseband A/D converters by a factor of two. A dual-receiver prototype designed and fabricated in 0.18-mum CMOS technology provides a sensitivity of -72 dBm with an EVM of -25 dB for 64 QAM signals while drawing 60.2 mW from a 1.8-V supply.

I. Introduction

The use of multiple antennas and receivers can substantially boost the performance in wireless communication. For example, antenna diversity and beamforming techniques improve the link budget considerably. Moreover, multiple-input-multiple-output (MIMO) systems can raise the channel capacity in the presence of multipath fading and have been adopted by the IEEE 802.11n standard. Since the brute force method of duplicating the entire receive path for each additional antenna entails a significant area and power penalty, it is desirable to share as much of the receiver among the antennas as possible.