Experimental Body-input Three-stage DC offset Calibration Scheme for Memristive Crossbar

TL;DR

This paper introduces an experimental three-stage DC offset calibration scheme for memristive crossbars, improving accuracy in neuromorphic circuits by reducing offset voltages through a novel biasing method.

Contribution

The paper presents a new three-stage calibration method for DC offset correction in memristive crossbars, validated through experimental results on a 130 nm CMOS chip with OxRAM memristors.

Findings

Calibration reduces offset voltage significantly

Method limited mainly by mismatch and electrical noise

Validated on a custom PCB with experimental data

Abstract

Reading several ReRAMs simultaneously in a neuromorphic circuit increases power consumption and limits scalability. Applying small inference read pulses is a vain attempt when offset voltages of the read-out circuit are decisively more. This paper presents an experimental validation of a three-stage calibration scheme to calibrate the DC offset voltage across the rows of the memristive crossbar. The proposed method is based on biasing the body terminal of one of the differential pair MOSFETs of the buffer through a series of cascaded resistor banks arranged in three stages: coarse, fine and finer stages. The circuit is designed in a 130 nm CMOS technology, where the OxRAM-based binary memristors are built on top of it. A dedicated PCB and other auxiliary boards have been designed for testing the chip. Experimental results validate the presented approach, which is only limited by mismatch and electrical noise.