Abstract: The on-chip voltage reference in 10 bit 40MSPS ADC has been designed. It features high precision, small area, etc. The band-gap reference is used for its basic configuration. Other innovations include a novel type CMOS operational amplifier with high gain, a wide input range with a view to improving the reference precision and two group voltage references RET and REB, the difference between which acts as the comparative voltage reference to reduce the reference absolute error. The Hspice simulation with Chart CMOS 0.35 μm shows that the op-amp gain is 88 dB, that the standard deviation of the voltage reference is lower than 5 mV and that the temperature coefficient is lower than 10^-4/(℃). The testing result shows that the designed voltage reference can meet ADC need after taping out.

Key words: operational amplifier, power supply rejection, temperature coe(fficient), ADC, band-gap reference voltage