Four-Element Wide Modulated Bandwidth MIMO Receiver With >35-dB Interference Cancellation

Active control of interference is necessary with increased cell density, more complicated environmental reflections, and coexistence of multiple networks for next-generation wireless communications. The existing radio receiver architectures for spatial interference cancellation (SpICa) are limited by the spatial nulls created by a phased-antenna array (PAA) and cannot cover wide modulated bandwidths (BWs). We propose a discrete-time-delay-compensating technique for canceling spatial interferences with wide modulated BWs to reduce the dynamic range requirement for the data converter. Integral to the proposed circuit is a switched-capacitor-based multiply-and-accumulate processor that incorporates a reconfigurable phase interpolator and time interleaver for precise digitally tunable delays and multiplication of the input signal to an orthogonal matrix. The digital time interleaver enables 5-ps resolution with a reconfigurable range up to 15 ns. The measured results demonstrate greater than 35-dB SpICa over 80-MHz modulated BWs in the 65-nm CMOS with 52 mW of power consumption.