Accurate dynamic-feedback CMOS cross-quad suitable for low-voltage operation

This paper presents the implementation of a crossquad circuit suitable for low-voltage operation. The proposed cell exploits a dynamic positive feedback gm boosting technique to achieve linear voltage-to-current conversion, while it manages to work with low-voltage with no extra bias current and minimal additional hardware. Results for a 0.5 m CMOS implementation supplied at 3 V show a 0.972 % voltage-tocurrent accuracy, improving the 0.867 % accuracy of a previously reported cross-quad topology also suitable for lowvoltage operation which is based on folded transistors. Ministerio de Ciencia e Innovación (PET2007-00336, PET2008-0021) Agencia Española de Cooperación Internacional para el desarrollo - Programa de Cooperación Interuniversitaria e Investigación Científica (AECI-PCI) (A/018704/08) Universidad de Zaragoza (UZ2008-TEC-08)