Linearisation of Digital-to-Analog Converters by Model Predictive Control

Abstract

Digital-to-analogue converters (DACs) are used to reconstruct digital quantised signals in the analog domain. Practical DACs exhibit several non-ideal effects e.g., principally integral non-linearity (INL). INL is caused by element mismatch, meaning actual output levels deviate from ideal counterparts causing signal distortion. To reduce this error a method employing moving horizon optimal control is proposed where INL has been integrated into the model. The model is built by precisely measuring the INL of the physical device and organising the data into a lookup table. Previous attempts at using moving horizon optimal quantiser (MHOQ) have assumed ideal quantisation, and are therefore unable to reduce the impact of INL. Several other methods exist that can linearise and mitigate the impact of INL but have significant drawbacks such as lack of guaranteed stability, complexity, and the need to use specialised and custom circuit topologies that cannot be replicated with off-the-shelf equipment. The effectiveness of the proposed method is demonstrated via simulations as well as experiments on a common off-the-shelf DAC.