A Mixed Signal MIMO Beamforming Receiver Richard Tseng, Ada S. Y. Poon, Yun Chiu

1. Accuracy: • MSE α 1/M2 • Cost: • M LO Phases • M Mixers/Ant. Linear Reconstruction Nonlinear Expansion Decisions Direct Conversion Implementation - in the phase domain Digital Domain Analog Domain Transconductance Stage Mixer Core Signal Combiner A Mixed Signal MIMO Beamforming Receiver Richard Tseng, Ada S. Y. Poon, Yun Chiu Current MIMO Implementations Proposed Implementation • Large number of analog components • Strong interferers easily saturate the ADCs, rendering any MIMO algorithm useless. • Most research activities focus on the VLSI implementation of various MIMO algorithms and do not solve the critical problem. • Simplify analog circuits, move complexity to the digital domain • Solve dynamic range problem by performing beamforming and signal combining in the analog domain • Many MIMO algorithms still applicable in analog domain, greatly relaxes circuit requirements. Three Pronged Approach Digital algorithm Novel circuits Scalable Architecture • Quantization algorithm based on frame theory and stochastic approximation. • Complex multiplier architecture scales up to multiple LO signals and high frequencies • Core DLL runs at a lower frequency • Edges combined to produce high • frequency LO signals • Accurate complex multiplication • Insensitive to phase and gain mismatch • Copying of signals allows circuit component reuse • Algorithm MSE can be reduced to • arbitrarily small values This work is supported by C2S2/DARPA