Patent ID: 11269629

Abstract:
Many signal processing, machine learning and scientific computing applications require a large number of multiply-accumulate (MAC) operations. This type of operation is demanding in both computation and memory. Process in memory has been proposed as a new technique that computes directly on a large array of data in place, to eliminate expensive data movement overhead. To enable parallel multi-bit MAC operations, both width- and level-modulating memory word lines are applied. To improve performance and provide tolerance against process-voltage-temperature variations, a delay-locked loop is used to generate fine unit pulses for driving memory word lines and a dual-ramp Single-slope ADC is used to convert bit line outputs. The concept is prototyped in a 180 nm CMOS test chip made of four 320×64 compute-SRAMs, each supporting 128× parallel 5 b×5 b MACs with 32 5 b output ADCs and consuming 16.6 mW at 200 MHz.