| Bandgap reference(BGR) source is a temperature insensitive pricise reference source. A zero temperature coefficient(ZTC) voltage combines a weighted negative TC VBE with a positive TC VT. The relative weighting of the voltage added is usually adjusted by trimming the ratio of resistors. The model of resistors in standard CMOS technology may not be reliable. Usually, laser trimming and more area are needed within resistors, that leads to high cost and low efficiency. The resistorless bandgap reference adjust TC constant by inverse function technology together with ratiod MOS transitors. This circuit fits digital technology batter and simplify the manufacturing process,especially in SOC.High-order temperature compensation has been develop to reduce the inaccuracy of bandgap reference without resistors. Unfortunately, traditional ways of compensation dosen’t work without resistors. In this paper, a high precision bandgap reference without resistors was proposed with VBE linearization high-order compensation. The theory of temperature compensation of both traditional and resistorless bandgap reference was discussed. Cascode current mirror and a pair additional current mirror was introduced into inverse function circuit to hold the current ratio and improve PSRR. A self-biseing current source provide stable positive and zero TC current was disgned. Combining inverse function circuit with two different TC current, the high-order terms in VBE versus temperature was eliminated, came up with a high-performance, low-TC reference voltage.Based on0.5μm BCD technology and4-6.5V voltage supply, simulation results show that: the reference voltage is1.18V, the effective temperature coefficient of output voltage is9.52ppm/℃(-45-125℃), PSRR at low frequency is-50dB, line regulation is7.42mV/V, and the total power dissipation is about490μW. This circuit performances as good as a mature traditional bandgap reference, and the new compensation theory was proved. |
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