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 - in the phase domain Analog Domain Digital Domain Direct Conversion Implementation Nonlinear Expansion Linear Reconstruction Decisions 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 Quantization algorithm based on frame theory and stochastic approximation. Signal Combiner Mixer Core Transconductance Stage Accuracy: MSE α 1/M2 Cost: M LO Phases M Mixers/Ant. 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