A Low-Noise High-Precision CMOS Bandgap Reference with Chopper Stabilization and Trimming Technique

This work presents a low-noise, high-precision CMOS bandgap reference with chopper stabilization and trimming technique. The chopper technology is used to eliminate the op-amp's distortion voltage and 1/f noise. The polysilicon resistor trimming network is used to improve the accuracy of the reference voltage and to be second-order temperature compensation. The comparator is used to increase the circuit's start-up reliability. Designed and simulated in 0.25μm CMOS technology, it supports an operating voltage range of 3 V- 5.5 V, the trim code value of 0 - 63 for the reference voltage, and the trim voltage range of 1.178 V - 1.292V, an operating temperature range of -40°C - 125°C. Under typical conditions (supply voltage of 3V, operating temperature of 27°C, and process angle of TT), the bandgap reference output voltage is 1.22V, and the noise at 1Hz is 162nV/sqrt(Hz), the noise at 100Hz is 105.5nV/sqrt(Hz). The power supply rejection ratio at 1Hz is -85.6196dB. The start-up time of the circuit is about 4 μs. The temperature coefficient is 2.41ppm/°C. The loop gain is 82.2972dB and the phase margin is 88.146°. The circuits proposed in this paper are applied in a high-precision ADC chip, which has been successfully flowed using 0.25μm CMOS process.