A 1-V CMOS Current Reference With Temperature and Process Compensation

A 1-V current reference fabricated in a standard CMOS process is described. Temperature compensation is achieved from a bandgap reference core using a transimpedance amplifier in order to generate an intermediate voltage reference, V_REF. This voltage applied to the gate of a carefully sized nMOS output transistor provides a reference drain current, I_REF , nearly independent of temperature by mutual compensation of mobility and threshold voltage variations. The circuit topology allows for compensation of threshold voltage variation due to process parameters as well. The current reference has been fabricated in a standard 0.18-mum CMOS process. Results from nineteen samples measured over a temperature range of 0degC to 100degC , showed values of I_REF of 144.3 muA plusmn 7% and V_REF of 610.9 mV plusmn 2% due to the combined effect of temperature and process variations.