A 90 dB PSRR, 4 dBm EMI resistant, NMOS-only voltage reference using zero-VT active loads

Abstract

Electromagnetic Interference (EMI) disturbances coupled in the power supply of voltage and current references can severely degrade their performance, due to its finite Power Supply Rejection Ratio (PSRR). The design of a 90 dB PSRR, 4 dBm EMI resistant NMOS-Only Voltage Reference is herein presented. The Voltage Reference is designed based on the Zero Temperature Coefficient (ZTC) transistor point. The high-PSRR is obtained using zero-VT transistors as active loads in the open and feedback loop of the circuit. The final circuit was designed in a 130 nm CMOS process and occupies around 0.014 mm2 of silicon area while consuming just 1.15 μW. Post-layout simulations present a 206 mV of Voltage Reference with a Temperature Coefficient of 321 ppm/°C, for the temperature range from -55 to 125 °C. An EMI source of 4 dBm (1 Vpp) injected in the power supply, according to the Direct Power Injection (DPI) standard, yield in a maximum dc shift and Peak-to-peak ripple of -0.17 % and 822 μVpp, respectively.