Test vehicle for a wafer-scale field programmable gate array

Using laser defect avoidance to build large-area FPGAs

“…Furthermore, laser connections take only 10% to 25% the area of active switches and their control sections. 4 Researchers have used laser-link defect avoidance to build fully operational wafer-scale circuits in nine different designs applied to DSP filter and speech recognition systems, all in large, metal MCM packages. 2,3…”

“…The simulation starts with a defect-free array 4 and adds defects when a random number generated for each cell exceeds the failure probability. The failure probability depends on the number of defects already in the cell and its nearest neighbors.…”

“…Previous WSI systems used either large laser links or long transistors for power connections. 4 Our FPGA test vehicle uses a new device called the testable laser link, which combines a long laser link and a small transistor. 8 Activating the transistor section provides a modest connection (a 0.08-V drop) for low-frequency cell power checks.…”

“…In similar tests with a 2 × 5-matrix test vehicle, the shorter column substitutions produced smaller effects of 2% to 9% for N R = 1 to N R = 4. 4 This FPGA's relatively modest speed was a function of the fabrication process. We directly measured the delays from restructuring with active and laser links on the FPGA chip.…”