A gate leakage current based nano-ampere current reference generator using a dual threshold voltage 6-T voltage reference

Abstract

To realize nano-ampere current reference generator, a tunable 1.34 nA current reference generator is proposed by applying the reference voltage to a PMOSFET achieving low-temperature coefficients (TCs). Unlike the conventional resistors occupying a large die area, the area was significantly reduced by using the gate leakage PMOSFET. Furthermore, the area-efficient reference voltage based on MOSFETs operated at subthreshold rather than the accurate but power- and area-hungry bandgap reference was utilized. To cope with process variations, the reference current can be trimmed by four switches and is easy to be replicated. The proposed current generator was designed and fabricated on the die area of 0.0175 mm2 using 90 nm CMOS technology. The measured TC of the 308 mV voltage reference is 124 ppm °C−1 and the measured TC of the 1.34 nA current reference is 394 ppm °C−1 from 0 °C to 120 °C at a supply voltage of 0.75 V.