Low Voltage CMOS Current Mode Reference Circuit without Operational Amplifiers

In this paper, we propose the novel low voltage CMOS current mode reference circuit. It reduces the minimum supply voltage by consisting the subthreshold two stage operational amplifier (OPAMP) which is regarded as the combination of the proportional to absolute temperature (PTAT) and the complementary to absolute temperature (CTAT) current generators. It makes possible to implement without extra OPAMP. This proposed circuit has been designed and evaluated by SPICE simulation using TSMC 65 nm CMOS process with 3.3 V (2.5 V over-drive) transistor option. From simulation results, the line sensitivity is as good as 0.196%/V under the condition that the range of supply voltage (V-DD) is wide as 0.6 V to 3.0 V. The temperature coefficient is 71 ppm/degrees C under the condition that the temperature range is from -40 degrees C to 125 degrees C and V-DD = 0.6 V. The power supply rejection ratio (PSRR) is -47.7 dB when V-DD = 0.6 V and the noise frequency is 100 Hz. According to comparing the proposed circuit with prior current mode circuits, we could confirm the performance of the proposed circuit is better than that of prior circuits.