Low-Noise CMOS Bandgap Reference Generator Using Two-Level Chopping Technique

This paper presents a low-noise CMOS bandgap reference (BGR) circuit that uses two-level chopping technique to reduce errors caused by non-idealities of the OPAMP used in the design. Input referred offset voltage of the OPAMP is reduced on first level. On second level, OPAMP offset is further reduced along with the low-frequency 1/f noise caused by the input transistors of the two-stage Miller OPAMP. The design is fabricated in a 0.35μm 2P4M CMOS analog process. The proposed BGR was tested in a temperature chamber between -25oC and +125oC. Measurement results showed that the standard deviation of the BGR output voltage without chopping is 7 times higher than that of when chopping is enabled. The proposed two-level chopping technique is verified improving performance characteristics of conventional BGR circuit.