FPCAS: In-Memory Floating Point Computations for Autonomous Systems

Autonomous systems e.g., cars and drones generate vast amount of data from sensors that need to be processed in timely fashion to make accurate and safe decisions. Majority of these computations deal with Floating Point (FP) numbers. Conventional Von-Neumann computing paradigm suffers from overheads associated with data transfer. In-memory computing (IMC) can solve this challenge by processing the data locally. However, in-memory FP computing has not been investigated before. We propose F P arithmetic (adder/subtractor and multiplier) using Resistive RAM (ReRAM) crossbar based IMC. A novel shift circuitry is proposed to lower the shift overhead inherently present in the FP arithmetic. The proposed single precision FP adder consumes 335 pJ and 322 pJ for NAND-NAND and NOR-NOR based implementation for addition/subtraction, respectively. The proposed adder/subtractor improves latency, power and energy by 828X, 3.2X, and 3.7X, respectively, compared to MAGIC [1]. Furthermore, the proposed multiplier reduces energy per operation by 1.13X and improves performance by 4.4X compared to ReVAMP [2].