800-nA Process-and-Voltage-Invariant 106-dB PSRR PTAT Current Reference

This brief presents a novel process-and-voltage-invariant proportional to absolute temperature (PTAT) current reference. The proposed circuit is designed and fabricated in 180-nm mixed-mode CMOS technology. Measurement results show that the IPTAT varies only by ±2.4% (±3σ/mean) across 18 test chips. One thousand Monte Carlo simulation runs show that the maximum deviation (±3σ/mean) from the desired value of the PTAT current is ±5.4%. The proposed PTAT current reference uses a process, voltage, and temperature (PVT)-invariant resistor circuit having R_ON variation reduced by 4.2 times, as compared to a fixed biased MOSFET. The proposed PTAT current reference draws only 800-nA current from the supply voltage and also exhibits a high dc power supply rejection ratio (PSRR) of 106 dB. This brief also presents a PVT-invariant transconductance using the implemented PVT-invariant resistor.