A sub 1 V high PSRR CMOS bandgap voltage reference

A Bandgap circuit capable of generating a reference voltage of less than 1 V with high PSRR and low temperature sensitivity is proposed. High PSRR achieved by means of an improved current mode regulator which isolates the bandgap voltage from the variations and the noise of the power supply. A vigorous analytical approach is presented to provide a universal design guideline. The analysis unveils the sensitivity of the circuit characteristic to device parameters. The proposed circuit is fabricated in a 0.18μm CMOS technology and operates down to a supply voltage of 1.2 V. The circuit yields 20 ppm/°C of temperature coefficient in typical case and 50 ppm/°C of temperature coefficient in worst case over temperature range −40 to 140°C, 60 ppm/V of supply voltage dependence and 60 dB PSRR at 1 MHz without trimming or extra circuits for the curvature compensation. The entire circuit occupies 0.027 mm2 of die area and consumes 134μW from a 1.2 V supply voltage at room temperature. Twenty chips are tested to show the robustness of the topology and the measurement results are compared with Monte Carlo simulation and analysis.

► The modified structure of BG voltage reference enables the generation of sub 1.2V BG voltage reference.
► Combination of cascode current source and amplifier improves the PSRR of BG voltage circuit.
► Proper sizing of BG circuit elements reduces its sensitivity to PVT variation.