A massively parallel systolic-array architecture is proposed for the implementation of real-time VLSI spatio-temporal 3-D IIR frequency-planar filters at a throughput of one-frame-per-clock-cycle (OFPCC). The architecture is based on a differential-form transfer function and is of low circuit complexity compared with the direct-form architecture. A 3-D look-ahead (LA) form of the transfer function is proposed for maximizing the speed of the implementation, which has a nonseparable 3-D transfer function. The systolic array enables real-time implementation of 3-D IIR frequency-planar filters at radio-frequency (RF) frame-rates and is therefore a suitable building block for 3-D IIR digital filters having beam- and cone-shaped passbands as required for smart-antenna-array beam-forming applications involving the broadband spatio-temporal filtering of plane-waves. The fixed-point systolic-array implementation have a throughput of OFPCC and the tested real-time prototype achieves frame (clock) sample frequencies of up to 90 MHz using one Xilinx Virtex-4 sx35-10ff668 FPGA device.