A 1-V PTAT current reference circuit with 0.05%/V current sensitivity to VDD

Abstract

This paper presents a CMOS PTAT current reference circuit which is robust against process and supply voltage variations over a wide voltage and temperature range, i.e. from 0.9 V to 2.5 V and from -40° C to 125° C, respectively. Two implementations of the same circuit were designed for comparison: the first one uses core transistors (1.1 V), while the second one employs IO transistors (2.5 V). The circuit uses a PMOS version of a conventional PTAT current generator with a PMOS self-cascode MOSFET and a PMOS feedback amplifier to enhance the circuit performance. Simulation results have shown a PTAT current sensitivity to the supply voltage of 2.9%/V @ 27° C (from 0.9 V to 1.5 V) and of 0.05%/V @ 27° C (from 1 V to 2.5 V) for core and IO transistors implementations, respectively, and a nearly constant current spread over temperature, with a maximum variation of 10% (3σ) for both ones.