A temperature and process compensation circuit for resistive-based in-memory computing arrays

In-Memory Computing (IMC) architectures promise increased energy-efficiency for embedded artificial intelligence. Many IMC circuits rely on analog computation, which is more sensitive to process and temperature variations than digital. Thus, maintaining a suitable computation accuracy may require process and temperature compensation. Focusing on resistive-based IMC architectures, we propose an ultra-low power circuit to compensate for the temperature and process-based non-linearities of resistive computing elements. The proposed circuit, implemented in 65 nm CMOS can provide a temperature coefficient between 10 and 1938 ppm/degrees C for a wide temperature range (-40 degrees C to 80 degrees C) and output current range (few pA up to 600 nA) at 1.2 V operating voltage. Used in a resistive IMC array, the variation of output currents from each multiply-accumulate (MAC) operation can be reduced by up to 84% to maintain computation accuracy across process and temperature variations.